Former environment minister Owen Paterson has called for the UK to scrap its climate change targets.

In a speech to the Global Warming Policy Foundation, he cited “considerable uncertainty” over the impact of carbon emissions on global warming – a line that was displayed prominently in coverage by the Telegraph and the Daily Mail.

Paterson is far from alone: climate change debate has been suffused with appeals to ‘uncertainty’ to delay policy action. Who hasn’t heard politicians or media personalities use uncertainty associated with some aspects of climate change to claim that the science is ‘not settled‘?

Over in the US, this sort of thinking pops up quite often in the opinion pages of The Wall Street Journal. Its most recent article, by Professor Judith Curry, concludes that the ostensibly slowed rate of recent warming gives us “more time to find ways to decarbonise the economy affordably.”

What we do know – inspite of ‘uncertainty’

At first glance, avoiding interference with the global economy may seem advisable when there is uncertainty about the future rate of warming or the severity of its consequences.

But delaying action because the facts are presumed to be unreliable reflects a misunderstanding of the science of uncertainty.

Simply because a crucial parameter such as the climate system’s sensitivity to greenhouse gas emissions is expressed as a range – for example, that under some emissions scenarios we will experience 2.6°C to 4.8ºC of global warming or 0.3 to 1.7 m of sea level rise by 2100 – does not mean that the underlying science is poorly understood. We are very confident that temperatures and sea levels will rise by a considerable amount.

Perhaps more importantly, just because some aspects of climate change are difficult to predict (will your county experience more intense floods in a warmer world, or will the floods occur down the road?) does not negate our wider understanding of the climate.

We can’t yet predict the floods of the future but we do know that precipitation will be more intense because more water will be stored in the atmosphere on a warmer planet.

This idea of uncertainty might be embedded deeply within science but is no one’s friend and it should be minimised to the greatest extent possible. It is an impetus to mitigative action rather than a reason for complacency.

Uncertainty means more risk – not less

There are three key aspects of scientific uncertainty surrounding climate change projections that exacerbate rather than ameliorate the risks to our future.

First, uncertainty has an asymmetrical effect on many climatic quantities. For example, a quantity known as Earth system sensitivity, which tells us how much the planet warms for each doubling of atmospheric carbon dioxide concentration, has been estimated to be between 1.5°C to 4.5ºC.

However, it is highly unlikely, given the well-established understanding of how carbon dioxide absorbs long-wave radiation, that this value can be below 1ºC. There is a possibility, however, that sensitivity could be higher than 4.5ºC.

For fundamental mathematical reasons, the uncertainty favours greater, rather than smaller, climate impacts than a simple range suggests.

Uncertainty also makes adaptation harder

Second, the uncertainty in our projections makes adaptation to climate change more expensive and challenging. Suppose we need to build flood defences for a coastal English town.

If we could forecast a 1m sea level rise by 2100 without any uncertainty, the town could confidently build flood barriers 1m higher than they are today. However, although sea levels are most likely to rise by about 1m, we’re really looking at a range between 0.3m and 1.7m.

Therefore, flood defences must be at least 1.7m higher than today – 70cm higher than they could be in the absence of uncertainty. And as uncertainty increases, so does the required height of flood defences for non-negotiable mathematical reasons.

And the problem doesn’t end there, as there is further uncertainty in forecasts of rainfall occurrence, intensity and storm surges. This could ultimately mandate a 2 to 3m-high flood defence to stay on the safe side, even if the most likely prediction is for only a 1m sea-level rise.

Even then, as most uncertainty ranges are for 95% confidence, there is a 5% chance that those walls would still be too low. Maybe a town is willing to accept a 5% chance of a breach, but a nuclear power station cannot to take such risks.

Systemic uncertainties may be hiding the gravest of risks

Finally, some global warming consequences are associated with deep, so-called systemic uncertainty. For example, the combined impact on coral reefs of warmer oceans, more acidic waters and coastal run-off that becomes more silt-choked from more intense rainfalls is very difficult to predict.

But we do know, from decades of study of complex systems, that those deep uncertainties may camouflage particularly grave risks. This is particularly concerning given that more than 2.6 billion people depend on the oceans as their primary source of protein.

Similarly, warming of Arctic permafrost could promote the growth of CO₂-sequestering plants, the release of warming-accelerating methane, or both.

Warm worlds with very high levels of carbon dioxide did exist in the very distant past and these earlier worlds provide some insight into the response of the Earth system; however, we are accelerating into this new world at a rate that is unprecedented in Earth history, creating additional layers of complexity and uncertainty.

Uncertainty is not the same as ignorance

Increasingly, arguments against climate mitigation are phrased as “I accept that humans are increasing CO₂ levels and that this will cause some warming but climate is so complicated we cannot understand what the impacts of that warming will be.”

This argument is incorrect – uncertainty does not imply ignorance. Indeed, whatever we don’t know mandates caution. No parent would argue:

“I accept that if my child kicks lions, this will irritate them, but a range of factors will dictate how the lions respond; therefore I will not stop my child from kicking lions.”

The deeper the uncertainty, the more greenhouse gas emissions should be perceived as a wild and poorly understood gamble.

By extension, the only unequivocal tool for minimising climate change uncertainty is to decrease our greenhouse gas emissions.

Richard Pancost is Professor of Biogeochemistry, Director of the Cabot Institute at the University of Bristol. He receives funding from the NERC, the EU and the Leverhulme Trust.

Stephan Lewandowsky is Chair of Cognitive Psychology at the University of Bristol. He receives funding from the Australian Research Council, the World University Network, and the Royal Society.

This article was originally published on The Conversation. Read the original article.

When NASA researchers first saw data indicating a massive cloud of methane floating over the American Southwest, they found it so incredible that they dismissed it as an instrument error.

But as they continued analyzing data from the European Space Agency’s Scanning Imaging Absorption Spectrometer for Atmospheric Chartography instrument from 2002 to 2012, the ‘atmospheric hot spot’ kept appearing.

The team at NASA was finally able to take a closer look, and have now concluded that there is in fact a 2,500-square-mile cloud of methane – roughly the size of Delaware – floating over the Four Corners region, where the borders of Arizona, Colorado, New Mexico, and Utah all intersect.

This discovery follows the Intergovernmental Panel on Climate Change’s new estimates of methane’s ‘global warming potential’ (GWP): 34 over 100 years, and 86 over 20 years. That number reflects how much more powerful methane is than CO₂.

The methane cloud’s origin? Fossil fuel production

A report published by the NASA researchers in the journal Geophysical Research Letters concludes that “the source is likely from established gas, coal, and coalbed methane mining and processing.”

Indeed, the hot spot happens to be above New Mexico’s San Juan Basin, the most productive coalbed methane basin in North America.

Methane has been the focus of an increasing amount of attention, especially in regards to methane leaks from fracking for oil and natural gas.

Pockets of natural gas, which is 95-98% methane, are often found along with oil and simply burned off in a very visible process called ‘flaring’.

But scientists are starting to realize that far more methane is being released by the fracking boom than previously thought. And it appears that much of it is venting directly to the atmosphere, rather than being flared.

Fracking and horizontal drilling in the frame

Earlier this year, Cornell environmental engineering professor Anthony Ingraffea released the results of a study of 41,000 oil and gas wells that were drilled in Pennsylvania between 2000 and 2012.

He found that newer wells using fracking and horizontal drilling methods were far more likely to be responsible for fugitive emissions of methane.

According to the NASA researchers, the region of the American Southwest over which the 2,500-square-mile methane cloud is floating emitted 590,000 metric tons of methane every year between 2002 and 2012.

That’s almost 3.5 times the widely used estimates in the European Union’s Emissions Database for Global Atmospheric Research – and none of it was from fracking.

That should prompt a hard look at the entire fossil fuel sector, not just fracking, according to University of Michigan Professor Eric Kort, the lead researcher on the study:

“While fracking has become a focal point in conversations about methane emissions, it certainly appears from this and other studies that in the US, fossil fuel extraction activities across the board likely emit higher than inventory estimates.”

Mike G writes for DeSmogBlog, where this article was originally published.

Former environment minister Owen Paterson has called for the UK to scrap its climate change targets.

In a speech to the Global Warming Policy Foundation, he cited “considerable uncertainty” over the impact of carbon emissions on global warming – a line that was displayed prominently in coverage by the Telegraph and the Daily Mail.

Paterson is far from alone: climate change debate has been suffused with appeals to ‘uncertainty’ to delay policy action. Who hasn’t heard politicians or media personalities use uncertainty associated with some aspects of climate change to claim that the science is ‘not settled‘?

Over in the US, this sort of thinking pops up quite often in the opinion pages of The Wall Street Journal. Its most recent article, by Professor Judith Curry, concludes that the ostensibly slowed rate of recent warming gives us “more time to find ways to decarbonise the economy affordably.”

What we do know – inspite of ‘uncertainty’

At first glance, avoiding interference with the global economy may seem advisable when there is uncertainty about the future rate of warming or the severity of its consequences.

But delaying action because the facts are presumed to be unreliable reflects a misunderstanding of the science of uncertainty.

Simply because a crucial parameter such as the climate system’s sensitivity to greenhouse gas emissions is expressed as a range – for example, that under some emissions scenarios we will experience 2.6°C to 4.8ºC of global warming or 0.3 to 1.7 m of sea level rise by 2100 – does not mean that the underlying science is poorly understood. We are very confident that temperatures and sea levels will rise by a considerable amount.

Perhaps more importantly, just because some aspects of climate change are difficult to predict (will your county experience more intense floods in a warmer world, or will the floods occur down the road?) does not negate our wider understanding of the climate.

We can’t yet predict the floods of the future but we do know that precipitation will be more intense because more water will be stored in the atmosphere on a warmer planet.

This idea of uncertainty might be embedded deeply within science but is no one’s friend and it should be minimised to the greatest extent possible. It is an impetus to mitigative action rather than a reason for complacency.

Uncertainty means more risk – not less

There are three key aspects of scientific uncertainty surrounding climate change projections that exacerbate rather than ameliorate the risks to our future.

First, uncertainty has an asymmetrical effect on many climatic quantities. For example, a quantity known as Earth system sensitivity, which tells us how much the planet warms for each doubling of atmospheric carbon dioxide concentration, has been estimated to be between 1.5°C to 4.5ºC.

However, it is highly unlikely, given the well-established understanding of how carbon dioxide absorbs long-wave radiation, that this value can be below 1ºC. There is a possibility, however, that sensitivity could be higher than 4.5ºC.

For fundamental mathematical reasons, the uncertainty favours greater, rather than smaller, climate impacts than a simple range suggests.

Uncertainty also makes adaptation harder

Second, the uncertainty in our projections makes adaptation to climate change more expensive and challenging. Suppose we need to build flood defences for a coastal English town.

If we could forecast a 1m sea level rise by 2100 without any uncertainty, the town could confidently build flood barriers 1m higher than they are today. However, although sea levels are most likely to rise by about 1m, we’re really looking at a range between 0.3m and 1.7m.

Therefore, flood defences must be at least 1.7m higher than today – 70cm higher than they could be in the absence of uncertainty. And as uncertainty increases, so does the required height of flood defences for non-negotiable mathematical reasons.

And the problem doesn’t end there, as there is further uncertainty in forecasts of rainfall occurrence, intensity and storm surges. This could ultimately mandate a 2 to 3m-high flood defence to stay on the safe side, even if the most likely prediction is for only a 1m sea-level rise.

Even then, as most uncertainty ranges are for 95% confidence, there is a 5% chance that those walls would still be too low. Maybe a town is willing to accept a 5% chance of a breach, but a nuclear power station cannot to take such risks.

Systemic uncertainties may be hiding the gravest of risks

Finally, some global warming consequences are associated with deep, so-called systemic uncertainty. For example, the combined impact on coral reefs of warmer oceans, more acidic waters and coastal run-off that becomes more silt-choked from more intense rainfalls is very difficult to predict.

But we do know, from decades of study of complex systems, that those deep uncertainties may camouflage particularly grave risks. This is particularly concerning given that more than 2.6 billion people depend on the oceans as their primary source of protein.

Similarly, warming of Arctic permafrost could promote the growth of CO₂-sequestering plants, the release of warming-accelerating methane, or both.

Warm worlds with very high levels of carbon dioxide did exist in the very distant past and these earlier worlds provide some insight into the response of the Earth system; however, we are accelerating into this new world at a rate that is unprecedented in Earth history, creating additional layers of complexity and uncertainty.

Uncertainty is not the same as ignorance

Increasingly, arguments against climate mitigation are phrased as “I accept that humans are increasing CO₂ levels and that this will cause some warming but climate is so complicated we cannot understand what the impacts of that warming will be.”

This argument is incorrect – uncertainty does not imply ignorance. Indeed, whatever we don’t know mandates caution. No parent would argue:

“I accept that if my child kicks lions, this will irritate them, but a range of factors will dictate how the lions respond; therefore I will not stop my child from kicking lions.”

The deeper the uncertainty, the more greenhouse gas emissions should be perceived as a wild and poorly understood gamble.

By extension, the only unequivocal tool for minimising climate change uncertainty is to decrease our greenhouse gas emissions.

Richard Pancost is Professor of Biogeochemistry, Director of the Cabot Institute at the University of Bristol. He receives funding from the NERC, the EU and the Leverhulme Trust.

Stephan Lewandowsky is Chair of Cognitive Psychology at the University of Bristol. He receives funding from the Australian Research Council, the World University Network, and the Royal Society.

This article was originally published on The Conversation. Read the original article.

When NASA researchers first saw data indicating a massive cloud of methane floating over the American Southwest, they found it so incredible that they dismissed it as an instrument error.

But as they continued analyzing data from the European Space Agency’s Scanning Imaging Absorption Spectrometer for Atmospheric Chartography instrument from 2002 to 2012, the ‘atmospheric hot spot’ kept appearing.

The team at NASA was finally able to take a closer look, and have now concluded that there is in fact a 2,500-square-mile cloud of methane – roughly the size of Delaware – floating over the Four Corners region, where the borders of Arizona, Colorado, New Mexico, and Utah all intersect.

This discovery follows the Intergovernmental Panel on Climate Change’s new estimates of methane’s ‘global warming potential’ (GWP): 34 over 100 years, and 86 over 20 years. That number reflects how much more powerful methane is than CO₂.

The methane cloud’s origin? Fossil fuel production

A report published by the NASA researchers in the journal Geophysical Research Letters concludes that “the source is likely from established gas, coal, and coalbed methane mining and processing.”

Indeed, the hot spot happens to be above New Mexico’s San Juan Basin, the most productive coalbed methane basin in North America.

Methane has been the focus of an increasing amount of attention, especially in regards to methane leaks from fracking for oil and natural gas.

Pockets of natural gas, which is 95-98% methane, are often found along with oil and simply burned off in a very visible process called ‘flaring’.

But scientists are starting to realize that far more methane is being released by the fracking boom than previously thought. And it appears that much of it is venting directly to the atmosphere, rather than being flared.

Fracking and horizontal drilling in the frame

Earlier this year, Cornell environmental engineering professor Anthony Ingraffea released the results of a study of 41,000 oil and gas wells that were drilled in Pennsylvania between 2000 and 2012.

He found that newer wells using fracking and horizontal drilling methods were far more likely to be responsible for fugitive emissions of methane.

According to the NASA researchers, the region of the American Southwest over which the 2,500-square-mile methane cloud is floating emitted 590,000 metric tons of methane every year between 2002 and 2012.

That’s almost 3.5 times the widely used estimates in the European Union’s Emissions Database for Global Atmospheric Research – and none of it was from fracking.

That should prompt a hard look at the entire fossil fuel sector, not just fracking, according to University of Michigan Professor Eric Kort, the lead researcher on the study:

“While fracking has become a focal point in conversations about methane emissions, it certainly appears from this and other studies that in the US, fossil fuel extraction activities across the board likely emit higher than inventory estimates.”

Mike G writes for DeSmogBlog, where this article was originally published.

Former environment minister Owen Paterson has called for the UK to scrap its climate change targets.

In a speech to the Global Warming Policy Foundation, he cited “considerable uncertainty” over the impact of carbon emissions on global warming – a line that was displayed prominently in coverage by the Telegraph and the Daily Mail.

Paterson is far from alone: climate change debate has been suffused with appeals to ‘uncertainty’ to delay policy action. Who hasn’t heard politicians or media personalities use uncertainty associated with some aspects of climate change to claim that the science is ‘not settled‘?

Over in the US, this sort of thinking pops up quite often in the opinion pages of The Wall Street Journal. Its most recent article, by Professor Judith Curry, concludes that the ostensibly slowed rate of recent warming gives us “more time to find ways to decarbonise the economy affordably.”

What we do know – inspite of ‘uncertainty’

At first glance, avoiding interference with the global economy may seem advisable when there is uncertainty about the future rate of warming or the severity of its consequences.

But delaying action because the facts are presumed to be unreliable reflects a misunderstanding of the science of uncertainty.

Simply because a crucial parameter such as the climate system’s sensitivity to greenhouse gas emissions is expressed as a range – for example, that under some emissions scenarios we will experience 2.6°C to 4.8ºC of global warming or 0.3 to 1.7 m of sea level rise by 2100 – does not mean that the underlying science is poorly understood. We are very confident that temperatures and sea levels will rise by a considerable amount.

Perhaps more importantly, just because some aspects of climate change are difficult to predict (will your county experience more intense floods in a warmer world, or will the floods occur down the road?) does not negate our wider understanding of the climate.

We can’t yet predict the floods of the future but we do know that precipitation will be more intense because more water will be stored in the atmosphere on a warmer planet.

This idea of uncertainty might be embedded deeply within science but is no one’s friend and it should be minimised to the greatest extent possible. It is an impetus to mitigative action rather than a reason for complacency.

Uncertainty means more risk – not less

There are three key aspects of scientific uncertainty surrounding climate change projections that exacerbate rather than ameliorate the risks to our future.

First, uncertainty has an asymmetrical effect on many climatic quantities. For example, a quantity known as Earth system sensitivity, which tells us how much the planet warms for each doubling of atmospheric carbon dioxide concentration, has been estimated to be between 1.5°C to 4.5ºC.

However, it is highly unlikely, given the well-established understanding of how carbon dioxide absorbs long-wave radiation, that this value can be below 1ºC. There is a possibility, however, that sensitivity could be higher than 4.5ºC.

For fundamental mathematical reasons, the uncertainty favours greater, rather than smaller, climate impacts than a simple range suggests.

Uncertainty also makes adaptation harder

Second, the uncertainty in our projections makes adaptation to climate change more expensive and challenging. Suppose we need to build flood defences for a coastal English town.

If we could forecast a 1m sea level rise by 2100 without any uncertainty, the town could confidently build flood barriers 1m higher than they are today. However, although sea levels are most likely to rise by about 1m, we’re really looking at a range between 0.3m and 1.7m.

Therefore, flood defences must be at least 1.7m higher than today – 70cm higher than they could be in the absence of uncertainty. And as uncertainty increases, so does the required height of flood defences for non-negotiable mathematical reasons.

And the problem doesn’t end there, as there is further uncertainty in forecasts of rainfall occurrence, intensity and storm surges. This could ultimately mandate a 2 to 3m-high flood defence to stay on the safe side, even if the most likely prediction is for only a 1m sea-level rise.

Even then, as most uncertainty ranges are for 95% confidence, there is a 5% chance that those walls would still be too low. Maybe a town is willing to accept a 5% chance of a breach, but a nuclear power station cannot to take such risks.

Systemic uncertainties may be hiding the gravest of risks

Finally, some global warming consequences are associated with deep, so-called systemic uncertainty. For example, the combined impact on coral reefs of warmer oceans, more acidic waters and coastal run-off that becomes more silt-choked from more intense rainfalls is very difficult to predict.

But we do know, from decades of study of complex systems, that those deep uncertainties may camouflage particularly grave risks. This is particularly concerning given that more than 2.6 billion people depend on the oceans as their primary source of protein.

Similarly, warming of Arctic permafrost could promote the growth of CO₂-sequestering plants, the release of warming-accelerating methane, or both.

Warm worlds with very high levels of carbon dioxide did exist in the very distant past and these earlier worlds provide some insight into the response of the Earth system; however, we are accelerating into this new world at a rate that is unprecedented in Earth history, creating additional layers of complexity and uncertainty.

Uncertainty is not the same as ignorance

Increasingly, arguments against climate mitigation are phrased as “I accept that humans are increasing CO₂ levels and that this will cause some warming but climate is so complicated we cannot understand what the impacts of that warming will be.”

This argument is incorrect – uncertainty does not imply ignorance. Indeed, whatever we don’t know mandates caution. No parent would argue:

“I accept that if my child kicks lions, this will irritate them, but a range of factors will dictate how the lions respond; therefore I will not stop my child from kicking lions.”

The deeper the uncertainty, the more greenhouse gas emissions should be perceived as a wild and poorly understood gamble.

By extension, the only unequivocal tool for minimising climate change uncertainty is to decrease our greenhouse gas emissions.

Richard Pancost is Professor of Biogeochemistry, Director of the Cabot Institute at the University of Bristol. He receives funding from the NERC, the EU and the Leverhulme Trust.

Stephan Lewandowsky is Chair of Cognitive Psychology at the University of Bristol. He receives funding from the Australian Research Council, the World University Network, and the Royal Society.

This article was originally published on The Conversation. Read the original article.

When NASA researchers first saw data indicating a massive cloud of methane floating over the American Southwest, they found it so incredible that they dismissed it as an instrument error.

But as they continued analyzing data from the European Space Agency’s Scanning Imaging Absorption Spectrometer for Atmospheric Chartography instrument from 2002 to 2012, the ‘atmospheric hot spot’ kept appearing.

The team at NASA was finally able to take a closer look, and have now concluded that there is in fact a 2,500-square-mile cloud of methane – roughly the size of Delaware – floating over the Four Corners region, where the borders of Arizona, Colorado, New Mexico, and Utah all intersect.

This discovery follows the Intergovernmental Panel on Climate Change’s new estimates of methane’s ‘global warming potential’ (GWP): 34 over 100 years, and 86 over 20 years. That number reflects how much more powerful methane is than CO₂.

The methane cloud’s origin? Fossil fuel production

A report published by the NASA researchers in the journal Geophysical Research Letters concludes that “the source is likely from established gas, coal, and coalbed methane mining and processing.”

Indeed, the hot spot happens to be above New Mexico’s San Juan Basin, the most productive coalbed methane basin in North America.

Methane has been the focus of an increasing amount of attention, especially in regards to methane leaks from fracking for oil and natural gas.

Pockets of natural gas, which is 95-98% methane, are often found along with oil and simply burned off in a very visible process called ‘flaring’.

But scientists are starting to realize that far more methane is being released by the fracking boom than previously thought. And it appears that much of it is venting directly to the atmosphere, rather than being flared.

Fracking and horizontal drilling in the frame

Earlier this year, Cornell environmental engineering professor Anthony Ingraffea released the results of a study of 41,000 oil and gas wells that were drilled in Pennsylvania between 2000 and 2012.

He found that newer wells using fracking and horizontal drilling methods were far more likely to be responsible for fugitive emissions of methane.

According to the NASA researchers, the region of the American Southwest over which the 2,500-square-mile methane cloud is floating emitted 590,000 metric tons of methane every year between 2002 and 2012.

That’s almost 3.5 times the widely used estimates in the European Union’s Emissions Database for Global Atmospheric Research – and none of it was from fracking.

That should prompt a hard look at the entire fossil fuel sector, not just fracking, according to University of Michigan Professor Eric Kort, the lead researcher on the study:

“While fracking has become a focal point in conversations about methane emissions, it certainly appears from this and other studies that in the US, fossil fuel extraction activities across the board likely emit higher than inventory estimates.”

Mike G writes for DeSmogBlog, where this article was originally published.

Former environment minister Owen Paterson has called for the UK to scrap its climate change targets.

In a speech to the Global Warming Policy Foundation, he cited “considerable uncertainty” over the impact of carbon emissions on global warming – a line that was displayed prominently in coverage by the Telegraph and the Daily Mail.

Paterson is far from alone: climate change debate has been suffused with appeals to ‘uncertainty’ to delay policy action. Who hasn’t heard politicians or media personalities use uncertainty associated with some aspects of climate change to claim that the science is ‘not settled‘?

Over in the US, this sort of thinking pops up quite often in the opinion pages of The Wall Street Journal. Its most recent article, by Professor Judith Curry, concludes that the ostensibly slowed rate of recent warming gives us “more time to find ways to decarbonise the economy affordably.”

What we do know – inspite of ‘uncertainty’

At first glance, avoiding interference with the global economy may seem advisable when there is uncertainty about the future rate of warming or the severity of its consequences.

But delaying action because the facts are presumed to be unreliable reflects a misunderstanding of the science of uncertainty.

Simply because a crucial parameter such as the climate system’s sensitivity to greenhouse gas emissions is expressed as a range – for example, that under some emissions scenarios we will experience 2.6°C to 4.8ºC of global warming or 0.3 to 1.7 m of sea level rise by 2100 – does not mean that the underlying science is poorly understood. We are very confident that temperatures and sea levels will rise by a considerable amount.

Perhaps more importantly, just because some aspects of climate change are difficult to predict (will your county experience more intense floods in a warmer world, or will the floods occur down the road?) does not negate our wider understanding of the climate.

We can’t yet predict the floods of the future but we do know that precipitation will be more intense because more water will be stored in the atmosphere on a warmer planet.

This idea of uncertainty might be embedded deeply within science but is no one’s friend and it should be minimised to the greatest extent possible. It is an impetus to mitigative action rather than a reason for complacency.

Uncertainty means more risk – not less

There are three key aspects of scientific uncertainty surrounding climate change projections that exacerbate rather than ameliorate the risks to our future.

First, uncertainty has an asymmetrical effect on many climatic quantities. For example, a quantity known as Earth system sensitivity, which tells us how much the planet warms for each doubling of atmospheric carbon dioxide concentration, has been estimated to be between 1.5°C to 4.5ºC.

However, it is highly unlikely, given the well-established understanding of how carbon dioxide absorbs long-wave radiation, that this value can be below 1ºC. There is a possibility, however, that sensitivity could be higher than 4.5ºC.

For fundamental mathematical reasons, the uncertainty favours greater, rather than smaller, climate impacts than a simple range suggests.

Uncertainty also makes adaptation harder

Second, the uncertainty in our projections makes adaptation to climate change more expensive and challenging. Suppose we need to build flood defences for a coastal English town.

If we could forecast a 1m sea level rise by 2100 without any uncertainty, the town could confidently build flood barriers 1m higher than they are today. However, although sea levels are most likely to rise by about 1m, we’re really looking at a range between 0.3m and 1.7m.

Therefore, flood defences must be at least 1.7m higher than today – 70cm higher than they could be in the absence of uncertainty. And as uncertainty increases, so does the required height of flood defences for non-negotiable mathematical reasons.

And the problem doesn’t end there, as there is further uncertainty in forecasts of rainfall occurrence, intensity and storm surges. This could ultimately mandate a 2 to 3m-high flood defence to stay on the safe side, even if the most likely prediction is for only a 1m sea-level rise.

Even then, as most uncertainty ranges are for 95% confidence, there is a 5% chance that those walls would still be too low. Maybe a town is willing to accept a 5% chance of a breach, but a nuclear power station cannot to take such risks.

Systemic uncertainties may be hiding the gravest of risks

Finally, some global warming consequences are associated with deep, so-called systemic uncertainty. For example, the combined impact on coral reefs of warmer oceans, more acidic waters and coastal run-off that becomes more silt-choked from more intense rainfalls is very difficult to predict.

But we do know, from decades of study of complex systems, that those deep uncertainties may camouflage particularly grave risks. This is particularly concerning given that more than 2.6 billion people depend on the oceans as their primary source of protein.

Similarly, warming of Arctic permafrost could promote the growth of CO₂-sequestering plants, the release of warming-accelerating methane, or both.

Warm worlds with very high levels of carbon dioxide did exist in the very distant past and these earlier worlds provide some insight into the response of the Earth system; however, we are accelerating into this new world at a rate that is unprecedented in Earth history, creating additional layers of complexity and uncertainty.

Uncertainty is not the same as ignorance

Increasingly, arguments against climate mitigation are phrased as “I accept that humans are increasing CO₂ levels and that this will cause some warming but climate is so complicated we cannot understand what the impacts of that warming will be.”

This argument is incorrect – uncertainty does not imply ignorance. Indeed, whatever we don’t know mandates caution. No parent would argue:

“I accept that if my child kicks lions, this will irritate them, but a range of factors will dictate how the lions respond; therefore I will not stop my child from kicking lions.”

The deeper the uncertainty, the more greenhouse gas emissions should be perceived as a wild and poorly understood gamble.

By extension, the only unequivocal tool for minimising climate change uncertainty is to decrease our greenhouse gas emissions.

Richard Pancost is Professor of Biogeochemistry, Director of the Cabot Institute at the University of Bristol. He receives funding from the NERC, the EU and the Leverhulme Trust.

Stephan Lewandowsky is Chair of Cognitive Psychology at the University of Bristol. He receives funding from the Australian Research Council, the World University Network, and the Royal Society.

This article was originally published on The Conversation. Read the original article.

The National Audit Office has begun an investigation into the controversial subsidy regime for the planned new Hinkley Point C nuclear plant in Somerset, a week after Brussels approved taxpayer support for the project.

The financial watchdog, which scrutinises public spending on behalf of parliament, said it would be checking whether the guaranteed prices of £92.50 a megawatt hour – double the current cost of electricity – represented ‘value for money’.

The NAO move, which follows pressure from a House of Commons committee, puts pressure on the government but has pleased green groups which believe nuclear is getting preferential treatment over windfarms.

NAO: ‘We wish to identify lessons learned’

“Our work will cover the Department of Energy and Climate Change’s commercial approach to securing this deal and the proposed terms of the contract, to report to parliament on value for money and the resulting risks which the Department must manage”, said the NAO in a formal statement.

“We will also wish to identify lessons learned to inform decisions on future ‘contracts for difference'”, it added – referring to the new funding mechanism for Hinkley and other low-carbon energy projects.

Last week the European Commission approved the subsidy scheme, citing government concessions on the project’s funding structure.

The parliamentary Environmental Audit Committee (EAC) had called this week for the NAO to hold a full inquiry into the government’s deal.

Joan Walley, the committee’s chair, said the “process and outcome” of the deal, as well as whether it represents value for money, should be investigated by the UK authorities now that it has been approved by Brussels.

DECC: ‘This is all perfectly ordinary’

A DECC spokesperson said: “This month the Commission agreed that Hinkley represents a good deal for both bill-payers and investors.

“It’s perfectly ordinary for the NAO to look into large investment contracts and we will be working with them as we move closer to finalising the contract. We will not go ahead with any contract unless it is good value for money.”

John Sauven, the executive director of Greenpeace UK, welcomed the NAO decision, saying: “The stitch-up concocted in Brussels will see two generations of UK consumers locked into paying billions of pounds to a mainly state-owned corporation in France in order to bankroll an outdated and risky source of energy.

“This is an extraordinarily bad use of public funds and ministers will have a tough time trying to justify it. This money would be better spent on clean technologies and energy saving measures, which don’t leave a legacy of radioactive waste, and benefit the UK economy while reducing carbon emissions.”

A legal challenge is being prepared

The decision by the NAO comes just days after Ecotricity and other renewable energy firms said they were considering a legal challenge against the Hinkley financing package.

Ecotricity, a wind farm operator and energy retailer, and Solarcentury, a solar power business, said the European Commission was wrong to conclude the Hinkley C aid would not be detrimental to other low-carbon power producers.

Hinkley C – a twin 1.6GW reactor nuclear power plant planned for Hinkley Point in Somerset – has been set a funding scheme paid for by consumers that will last for 35 years, much longer than any previous schemes enjoyed by renewables companies.

But EDF, which will build and Hinkley Point C, has defended the funding. It said: “Last week’s approval from the European commission demonstrates that agreements between the government and EDF are fair and balanced for consumers and investors alike.”

Terry Macalister is energy editor of the Guardian. He has been employed at the paper and website for 12 years and previously worked for the Independent and other national titles.

This article was originally published by The Guardian. It is republished by kind permission via the Guardian Environment Network.

The latest in the annual series of State of the UK’s Birds report, published today, shows alarming declines among 29 migrant species which nest in the UK in summer and spend the winter around the Mediterranean, or in Africa south of the Sahara Desert.

The most dramatic declines are among species which winter in the humid zone of Africa – stretching across the continent from southern Senegal to Nigeria and beyond.

Of this group of species, which includes whinchat, nightingale, tree pipit and spotted flycatcher, 73% have declined since the late 1980s, 45% by more than half.

One of the most dramatic declines is that of the turtle dove with a decline of 88% since 1995. Heavy declines have also been recorded over the same period for wood warbler, down 66%; pied flycatcher, 53%; spotted flycatcher, 49%; cuckoo, 49%; nightingale, 43%; and yellow wagtail, 43%.

Species wintering furthest south in the Congo Basin (represented here by cuckoos, swifts and swallows) also show a substantial decline since the early 1980s.

But where are the problems occurring?

According to Martin Harper, RSPB’s Conservation Director, it’s hard to pinpoint where the problems lie for the species’ decline:

“Their nomadic lifestyle, requiring sites and resources spread over vast distances across the globe makes identifying and understanding the causes of decline extremely complex. The problems may be in the UK or in West Africa, or indeed on migration in between the two.”

However the birds’ decline may be linked to deforestation in West Africa’s rainforests, and the expansion of both rain-fed and irrigated agriculture, says the report:

“The loss and degradation of wetlands is widely reported as a result of damming of rivers, extraction of water for irrigation, as well as the conversion of floodplains to rice fields, and floodplain woodlands to agricultural land. Wooded savannah habitats have similarly been impacted by clearance for agriculture, wood fuel and grazing.

“Human-induced habitat changes such as these have all been compounded by climate change altering seasonal weather patterns. These habitats are essential for many birds, as they allow the birds to refuel in the autumn, and fatten up before spring migration. The loss and degradation of these habitats is an erosion of vital stepping stones on the birds’ migratory journey.”

Hunting and trapping

Another problem is hunting and trapping, which “has been reported as impacting migratory birds on passage and on the non-breeding grounds during both spring and autumn migrations. Losses can be enormous. For example, 2–4 million turtle doves are shot across a number of southern European countries each year.”

Birds can be taken in large numbers in certain areas, such as quails in Egypt and swallows in west and central Africa. However, “Assessing the population-level impact of hunting is difficult, as the relevant data do not exist.”

But Alan Law, Director of Biodiversity Delivery at Natural England adds that we also need to look closer to home.

“For some species, there is growing evidence of pressure on breeding success here in England. Our focus therefore is to ensure that well-managed habitats are available in this country so that migratory species can breed here successfully.“

For example, the drastic (88%) decline of turtle doves is also due to diminished breeding success in the UK. Recent research has revealed that around 96% of the UK’s turtle doves are carrying parasites which can cause the disease trichomonosis, which caused mortality in a number of adults and nestlings during the 2012 breeding season.

Smaller declines, even increases for short-distance migrants

Other birds wintering in the arid zone just below the Sahara desert have fluctuated considerably since 1970, but show a much smaller decline of less than 20% overall, with 67% of species maintaining stable populations. This group includes sand martin, whitethroat and sedge warbler.

And the species that winter north of the Sahara (the partial / European migrants) are doing well, with 56% experiencing an increase in numbers since the mid 1980s. This group includes blackcaps, meadow pipits, chiffchaffs and stonechats.

Still, “concern about migratory bird species is growing and future editions of the State of the UK’s Birds report will contain a regular update to the migratory bird indicator.”

To understand the changing status of the UK’s migratory birds, researchers need to understand more about what’s driving these declines. Evidence is currently being gathered from a variety of sources including tracking studies and on-the-ground surveys.