Quantcast
Climate

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.

Vulnerable Countries

“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.

Large-scale 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.”

YOU MIGHT ALSO LIKE

Scientists Confirm: 93% of Great Barrier Reef Now Bleached

Not Everyone Is Celebrating the Signing of the Paris Climate Agreement

Do the Koch Brothers Want to Mine the Grand Canyon for Uranium?

NOAA: Last Month Was by Far the Planet’s Warmest March Since Record Keeping Began

Show Comments ()
Sponsored
The two young Iowa vandals knocked over 50 hives and exposed the bees to deadly winter temperatures. Colby Stopa / Flickr

Two Boys Charged With Killing Half a Million Honeybees in Iowa

Two boys were charged with killing more than a half million bees at a honey business in Iowa last month.

"All of the beehives on the honey farm were destroyed and approximately 500,000 bees perished in the frigid temperatures," Sioux City police said in a release.

Keep reading... Show less

Are Microwaves Really as Bad for the Environment as Cars?

According to many headlines blared around the Internet this week, "microwaves are as damaging to the environment as cars." But this misleading information, based on a new study from the University of Manchester, hopefully doesn't make you feel guilty about zapping your next Hot Pocket.

The research, published in the journal Science of the Total Environment, found that microwave ovens across the European Union generate as much carbon dioxide as nearly 7 million cars and consume an estimated 9.4 terawatts per hour of electricity per year. Okay, that sounds like a lot. But also consider that there are about 130 million microwaves in Europe and some 291 million vehicles on its roads.

Keep reading... Show less

Monsanto's Roundup Destroys Healthy Microbes in Humans and in Soils

By Julie Wilson

We're only beginning to learn the importance of healthy gut bacteria to our overall health—and the relationship between healthy soil and the human microbiome.

We know that the human microbiome, often referred to as our "second brain," plays a key role in our health, from helping us digest the food we eat, to boosting our brain function and regulating our immune systems.

Keep reading... Show less
Interior Sec. Ryan Zinke refused to meet with National Park System Advisory Board members last year, prompting most of them to quit. Gage Skidmore / Flickr

From National Parks to the EPA, Trump Administration Stiff-Arms Science Advisers

By Elliott Negin

The Trump administration's testy relationship with science reminds me of that old saying: Advice is least heeded when most needed.

Keep reading... Show less
Sponsored
Health
Shutterstock

8 Ways to Reduce Your Exposure to Hormone-Disrupting Chemicals

By Caroline Cox

What keeps you up at night? Sick kids, restless pets, the latest tragedy on the evening news, politics, wars, earthquakes, hurricanes, fires, money troubles, job stress, and family health and wellbeing? There is no shortage of concerns that make us all toss and turn.

But what keeps the chemical industry up at night? A couple of decades ago a senior Shell executive was asked this very question. The answer? Endocrine disruption.

Keep reading... Show less
Dave Atkinson / Flickr / CC BY-NC-ND 2.0

Why We'll March Again

This Sunday marks the first anniversary of the Women's March that happened on the day after Donald Trump's inauguration—the largest protest march in our nation's history. The Sierra Club was there that day, and we'll be there this year, too—at a significant moment for women's rights and justice.

Keep reading... Show less
Sponsored
Nils Axel-Morner gives an interview on the fringe of a meeting in Rome in October 2017. YouTube

Climate Denial Group Linked to Trump Admin Is Funding 'Research' on Sea Levels in Questionable Journals

By Graham Readfearn

A climate science denial group with links to President Trump's administration has been funding work to sow doubt that low-lying islands in the Pacific are at risk from rising sea levels.

The two researchers being funded—one of which is a well-known climate science denier—have targeted little known "open access" journals with dubious quality controls to get their work published, DeSmog has found.

Keep reading... Show less

It's Official: 2017 Was the Hottest Year Without an El Niño

The United Nations announced Thursday that 2017 was the hottest year on record without an El Niño event kicking up global annual temperatures.

Last year's average surface temperatures—driven by carbon dioxide and other greenhouse gas emissions—was 1.1 degree Celsius above pre-industrial times, putting the world on course to breach the internationally agreed "1.5°C" temperature barrier to avoid dangerous climate change set by the 2015 Paris climate agreement.

Keep reading... Show less
Sponsored

mail-copy

The best of EcoWatch, right in your inbox. Sign up for our email newsletter!