• Advertise
  • About us
  • Terms and Conditions
  • Contact us
Friday, April 23, 2021
Australian Times News
  • News
  • Lifestyle
    • Recipes
    • Video
    • Lotto Results
    • Technology
  • Entertainment
  • Travel
  • Sport
  • Expat Life
  • Move to Australia
No Result
View All Result
  • News
  • Lifestyle
    • Recipes
    • Video
    • Lotto Results
    • Technology
  • Entertainment
  • Travel
  • Sport
  • Expat Life
  • Move to Australia
No Result
View All Result
Australian Times News
No Result
View All Result
Home News

The climate won’t warm as much as we feared – but it will warm more than we hoped

A major new assessment has now calculated a range of 2.6–3.9℃. This implies that alarmingly high estimates from some recent climate models are unlikely.

The Conversation by The Conversation
24-07-2020 01:43
in News
The climate won’t warm as much as we feared

The climate won’t warm as much as we feared Photo by Jarosław Kwoczała on Unsplash

Steven Sherwood, UNSW; Eelco Rohling, Australian National University, and Katherine Marvel, NASA

We know the climate changes as greenhouse gas concentrations rise, but the exact amount of expected warming remains uncertain.

Shutterstock

Scientists study this in terms of “equilibrium climate sensitivity” – the temperature rise for a sustained doubling of carbon dioxide concentrations. Equilibrium climate sensitivity has long been estimated within a likely range of 1.5-4.5℃.

Under our current emissions trajectories, carbon dioxide concentrations in the atmosphere will likely double between 2060 and 2080, relative to concentrations before the industrial revolution. Before that, they had changed little for millennia.

A major new assessment has now calculated a range of 2.6–3.9℃. This implies that alarmingly high estimates from some recent climate models are unlikely, but also that comfortingly low estimates from other studies are even less likely.

More warming, greater impacts

Current and future climate change impacts include heatwaves, changing rainfall and drought patterns, and rising seas. Their severity depends on how much warming takes place.

Human activities are the main determinant of future temperatures, so a world with aggressive emissions control looks very different from a world in which emissions continue to increase.

AlsoRead...

Image by Gerd Altmann from Pixabay

Former NZ Govt spooks should be stopped from private spying, says party

23 April 2021
Photo by Tania Malréchauffé on Unsplash

New US climate pledge: Cut emissions 50% this decade, but can Biden make it happen?

23 April 2021

Even if we knew exactly how emissions would change in the future, the exact amount of warming that would result remains uncertain.

Four wind turbines at the end of a road, flanked by pale green-brown grass.
Drastic measures are still needed to curb climate change. Shutterstock

Our new equilibrium climate sensitivity analysis substantially reduces this uncertainty, by combining modern understanding of atmospheric physics with modern, historic, and prehistoric data using robust statistical methods.

The results indicate that substantial warming is much more solidly assured than we thought.

A matter of probabilities

In 1979, a farsighted report estimated for the first time that equilibrium climate sensitivity falls somewhere between 1.5℃ and 4.5℃. So if carbon dioxide concentrations doubled, global temperatures would eventually increase by somewhere in that range.

The width of this range is a problem. If equilibrium climate sensitivity lies at the low end of the range, climate change might be manageable with relatively relaxed national policies.

In contrast, a value near the high end would be catastrophic unless drastic action is taken to reduce emissions and draw carbon dioxide from the atmosphere.

Consequently, narrowing the equilibrium climate sensitivity range has been a key focus of climate science. While recent estimates haven’t really changed, climate scientists have learned a lot about how likely each outcome is.

For example, the 2013 Intergovernmental Panel on Climate Change (IPCC) report estimated a minimum two-thirds chance that equilibrium climate sensitivity falls within the 1.5–4.5℃ range. This implies there’s a chance of up to one-third that equilibrium climate sensitivity is lower or, worryingly, much higher.

The silhouette of a coal-burning power plant.
There’s only a 17% chance we’ll keep warming under 2℃, in the lowest global emissions scenario. Shutterstock

Recently, the potential for high climate sensitivities gained further attention after results from new climate models suggested values in excess of 5℃.

Our new assessment rules out low climate sensitivities, finding only a 5% chance that equilibrium climate sensitivity is below 2.3℃.

On the brighter side, we also find a low chance of it rising above 4.5℃. Constraining the precise probability of high equilibrium climate sensitivity range is difficult and depends to some extent on how the evidence is interpreted. Still, the alarming predictions of the new models appear unlikely.

We also find the chances of the world exceeding the 2℃ Paris Accord target by late this century are 17% under the lowest-emission scenario considered by the IPCC, 92% under a scenario that approximates current efforts, and 100% under the highest-emission scenario.

Why our study is different

The new assessment uses several strands of evidence. One is the recent, historical past since industrialisation, during which time temperatures have increased by about 1.1℃.

We compared this with knowledge about the natural drivers of climate over this period (such as slight changes in solar output and a few major volcanic eruptions), human-caused increases in atmospheric carbon dioxide and other greenhouse gases, and changes to the land surface.

Second, the assessment uses data for temperature changes and the underpinning natural processes from ice ages and warm periods in pre-historic times.

And third, it uses physical laws and present-day observations to evaluate how the planet responds to change, for example by examining brief warming or cooling episodes.

One conclusion is especially consistent between all lines of evidence. Unless the equilibrium climate sensitivity is larger than 2℃, we cannot explain either the warming we’ve already seen since industrialisation, the ice ages in Earth’s past, or certain aspects of how weather changes operate today.

This unequivocally demonstrates that relaxed efforts against carbon emissions will not avoid substantial warming.

This is not the final word

The new assessment is by no means the last word. It narrows the range, but we still don’t know exactly how hot it’s going to get.

Our assessment will also feed into the upcoming IPCC report, but the panellist will of course make an independent assessment. And further research may narrow the range more in the future.

While high sensitivities are unlikely, they cannot be completely excluded. But whether the temperature rise is moderate or high, the message is the same: drastic measures are needed to curb climate change.

Crucially, the new assessment clearly demonstrates that betting on low sensitivities and failing to implement drastic measures is risky to the point of irresponsibility.

Steven Sherwood, ARC Laureate Fellow, Climate Change Research Centre, UNSW; Eelco Rohling, Professor of Ocean and Climate Change, Australian National University, and Katherine Marvel, Associate Research Scientist, NASA

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Tags: SB001
DMCA.com Protection Status

SUBSCRIBE to our NEWSLETTER

Terms and Conditions

Don't Miss

Former NZ Govt spooks should be stopped from private spying, says party

by Mike Simpson
23 April 2021
Image by Gerd Altmann from Pixabay
at

New Zealand’s Green Party says it’s unacceptable that an ex-intelligence services agent should be used to spy on environmentalists.

Read more

New US climate pledge: Cut emissions 50% this decade, but can Biden make it happen?

by The Conversation
23 April 2021
Photo by Tania Malréchauffé on Unsplash
News

President Joe Biden announced an ambitious new national climate target at an online summit of world leaders on April 22,...

Read more

‘Self-driving’ cars are still a long way off. Here are three reasons why

by The Conversation
23 April 2021
Photo by Bram Van Oost on Unsplash
News

Most automated driving solutions available on the market today require human intervention. This puts them at level 1 (driver assistance,...

Read more

UK Weather forecast, alerts and UVB index, Friday 23 April 2021

by UK Weather
23 April 2021
weather
UK Weather

Be prepared for any weather with our daily forecast in the UK.

Read more

Too many Aussie businesses still reluctant to hire older workers

by Mike Simpson
23 April 2021
Amazon boss Jeff Bezos is 57 - would you hire him? Photo credit: Wikimedia Commons
News

Almost half of organisations surveyed said they were not keen to hire workers over a certain age, according to joint...

Read more

Morrison government quashes Victoria’s Belt and Road deal with China

by Michelle Grattan
23 April 2021
Photo by Sigmund on Unsplash
News

The Morrison government has cancelled the Belt and Road agreements Victoria has with China.

Read more

Free Horoscope for today, 23 April 2021

by Horoscopes
23 April 2021
Free Daily Horoscope - Astrology
Horoscopes

Keep your karma positive with these daily free horoscope readings!

Read more
Load More

Copyright © Blue Sky Publications Ltd. All Rights Reserved.
australiantimes.co.uk is a division of Blue Sky Publications Ltd. Reproduction without permission prohibited. DMCA.com Protection Status

  • About us
  • Write for Us
  • Advertise
  • Contact us
  • T&Cs, Privacy and GDPR
No Result
View All Result
  • News
  • Lifestyle
    • Recipes
    • Video
    • Lotto Results
    • Technology
  • Entertainment
  • Travel
  • Sport
  • Expat Life
  • Move to Australia

Copyright © Blue Sky Publications Ltd. All Rights Reserved.
australiantimes.co.uk is a division of Blue Sky Publications Ltd. Reproduction without permission prohibited. DMCA.com Protection Status