Scientists Share Why Keeping Warming Under 1.5 Degrees Celsius Is Crucial
With the possible prospect of the world warming dangerously and uncontrollably, half of one degree Celsius may sound like a negligible temperature change unlikely to make much difference to life on Earth.
But scientists say 0.5 C could make a crucial difference in some regions—particularly in developing countries in the tropics—that are already at great risk from climate change. The consequences could include higher sea level rise and extended heatwaves, threatening most tropical coral reefs.
Bill Hare, CEO of Climate Analytics and a member of the research team that has produced the cautionary report, said: “Our study shows that tropical regions—mostly developing countries that are already highly vulnerable to climate change—face the biggest rise in impacts between 1.5 C and 2 C.
“Our results add to a growing body of evidence showing that climate risks occur at lower levels than previously thought. They provide scientific evidence to support the call by vulnerable countries, such as the Least Developed Countries and Small Island Developing States, that a 1.5 C warming limit would substantially reduce the impacts of climate change.”
The Paris agreement on climate change being signed today in New York was concluded at last December’s UN climate conference. It aims to keep global average temperatures “well below” the 2 C previously agreed—and to pursue efforts to limit the increase to 1.5 C.
But the report by European researchers—published in Earth System Dynamics, an open access journal of the European Geosciences Union (EGU)—says they have found that there would be substantially different impacts for the two targets by 2100. They say the extra 0.5 C would mean a global sea-level rise of 10 centimeters, longer heatwaves and would put virtually all tropical coral reefs at risk.
“We found significant differences for all the impacts we considered,” said the study’s lead author, Carl-Friedrich Schleussner, a physicist at Climate Analytics.
“We analyzed the climate models used in the Intergovernmental Panel on Climate Change’s Fifth Assessment Report, focusing on the projected impacts at 1.5 C and 2 C warming at the regional level. We considered 11 different indicators, including extreme weather events, water availability, crop yields, coral reef degradation and sea-level rise.”
The team, including researchers from Germany, Switzerland, Austria and the Netherlands, identified a number of hotspots around the globe where projected climate impacts at 2 C are significantly more severe than at 1.5 C.
One of these is the Mediterranean region, already experiencing climate change-induced drying. With a global temperature increase of 1.5 C, the availability of fresh water in the region would be about 10 percent lower than in the late 20th century. But in a 2 C world, the researchers project that this reduction would double to about 20 percent.
In tropical regions, the half-a-degree difference in global temperature could damage crop yields, particularly in Central America and West Africa. On average, local tropical maize and wheat yields would fall twice as much with a 2 C temperature increase as with 1.5 C.
By 2100, tropical regions would also experience warm spells lasting up to 50 percent longer in a 2 C world than at 1.5 C. “For heat-related extremes, the additional 0.5 C increase marks the difference between events at the upper limit of present-day natural variability and a new climate regime, particularly in tropical regions,” Schleussner said.
The extra warming would also affect tropical coral reefs. Limiting warming to 1.5 C would provide a window of opportunity for some reefs to adapt to climate change, but a 2 C increase by 2100 would put virtually all of them at risk of severe degradation from coral bleaching.
Australian researchers say 93 percent of the Great Barrier Reef, off the coast of Queensland, is affected to some degree by bleaching. They say large-scale bleaching has also been found off Australia’s west coast.
In the EGU study, the researchers say they expect sea level to rise by about 50 cm by 2100 in a 2 C warmer world, 10 cm more than for 1.5 C warming. These levels are appreciably lower than some scientists expect.
“Sea level rise will slow down during the 21st century only under a 1.5 C scenario,” Dr. Schleussner warns.
One of his co-authors, Jacob Schewe, a climate physicist at the Potsdam Institute for Climate Impact Research, Germany, says it is necessary to account for natural variability, model uncertainties and other factors that could obscure the picture.
“We did that in our study,” he said. “And by focusing on key indicators at the regional level, we clearly show that there are significant differences in impacts between 1.5 C and 2 C.”
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EcoWatch Daily Newsletter
By Naomi Larsson
For centuries, the delicate silver dove has been a symbol of love and fidelity.
Biodiversity and Habitat Loss<p>Their near extinction is a symbol of the <a href="https://www.dw.com/en/global-biodiversity-outlook-targets-extinction-summit-new-york-pledge/a-54932895" target="_blank">biodiversity crisis</a> in the UK, largely driven by habitat destruction. Britain is now one of the countries with the most <a href="https://www.wwf.org.uk/future-of-UK-nature#:~:text=The%20UK%20is%20one%20of,than%20half%20are%20in%20decline" target="_blank">depleted nature</a> in the world according to the World Wildlife Fund. Half its plant and animal species are in decline and more than <a href="https://www.rspb.org.uk/about-the-rspb/about-us/media-centre/press-releases/let-nature-sing-wales/#:~:text=a%20natural%20tragedy.-,Over%2040%20million%20birds%20have%20vanished%20from%20UK%20skies%20in,unaware%20of%20the%20impending%20danger" target="_blank">40 million birds</a> have vanished in just half a century.</p><p>"[Turtle doves] are the canary in the [coal] mine because there are all these other species before it and after it," said Tree. "It's an umbrella for all the other species that are heading that way."</p><p>Turtle doves migrate south through Europe to sub-Saharan Africa between July and September, ending up in dry woodland and farmland areas of countries like Mali and Senegal for winter. </p><p>Droughts in West Africa and the Sahel region are believed to have contributed to the fall in turtle dove species recorded in northern Europe, with low rainfall reducing supplies of the seeds and insects the birds rely on for energy for the long journey home.</p>
Conservation and Farming<p><a href="https://www.operationturtledove.org/" target="_blank" rel="noopener noreferrer">Operation Turtle Dove,</a> a partnership project of charities including the Essex Wildlife trust, works with landowners and farmers to actively build turtle dove habitat.</p><p>Outten works with <a href="https://www.ebws.org.uk/birdsites/blue-house-farm-ewt-north-fambridge" target="_blank">Blue House Farm</a>, a 660-acre nature reserve in the UK county of Essex, where they have replicated weedy fallow plots. </p><p>"We work on it every year to make sure it's in the condition it needs to be with plants such as clovers and black medic," Outten said. "These plants are native to the landscape and produce the seed the birds feed on." </p><p>The birds eat a wide range of seeds from various plants that would have been abundant 50 or 100 years ago, added Guy Anderson, program manager for species recovery with The Royal Society for the Protection of Birds (RSPB). </p><p>"But it's simply true that with the gradual process of <a href="https://www.dw.com/en/farming-without-pesticides-how-can-we-make-agriculture-greener/a-52216796" target="_blank" rel="noopener noreferrer">intensifying our agricultural production</a>, the availability of those seeds has dropped and dropped," said Anderson.</p><p>Part of the project includes supplementary feeding — providing sources of food in the form of seed or grain. Under the Countryside Stewardship Scheme in England, farmers can receive financial support to create a turtle dove habitat. </p><p>Though they haven't recorded an increase in doves across the sites in the four years of working on the project, Outten said they are seeing improvements in how landowners and farmers manage habitat for the birds. </p>
A Turtle Dove Haven<p>The 3,500-acre Knepp Estate in West Sussex is another project taking a different approach and one of the few places where turtle dove numbers are increasing.</p><p>Isabella Tree and her husband Charlie Burrell converted their intensively farmed land into a rewilding project almost 20 years ago. They have let the land return to nature.</p><p>Just one year after they'd finished <a href="https://www.dw.com/en/uks-most-talented-architects-are-not-human/a-35952128" target="_blank">rewilding</a> the southern part of their property, they heard turtle doves for the first time. It's now a breeding hotspot for the birds with an estimated 19 pairs. Knepp is also home to <a href="https://www.rewildingbritain.org.uk/rewilding/rewilding-projects/knepp-estate" target="_blank" rel="noopener noreferrer">2% of the UK's population</a> of nightingales. </p><p>Tree is critical of supplementary feeding schemes that, in her view, are short term. She questions the chances of turtle doves getting to feed on scattered seeds before other mammals eat them first.</p>
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By Jessica Corbett
Green groups applauded Sen. Jeff Merkley on Wednesday for introducing a pioneering pair of bills that aim to "protect the long-term health and well-being of the American people and their economy from the catastrophic effects of climate chaos" by preventing banks and international financial institutions from financing fossil fuels.