Science

Climate Change Is Triggering More Heat Waves, Droughts, And Crop Yield Declines, Study Says

A new report from the United Nations’ body in charge of monitoring climate change details how global warming is already playing out on land to negative effect: magnifying heat waves and droughts, and contributing to desertification and declining crop yields.

And if global warming continues unchecked, worse impacts are yet to come, according to the Intergovernmental Panel on Climate Change’s special Climate Change and Land report released Thursday.

“As we continue to pour more and more carbon dioxide into the atmosphere, the Earth system has responded and it has continued to absorb more and more,” said Louis Verchot, one of the report’s more than 50 scientist authors, on a press call. “But the important finding of this report, I think, is this additional gift from nature is limited — it’s not going to continue forever.”

The release of greenhouse gases, or climate pollution, into the atmosphere in recent decades has led to uneven warming, and impacts, across the globe. The new report quantifies what’s happening specifically on the rapidly warming land, and how land use can curb or worsen future warming. (This report follows one published last October on the devastating impacts of 1.5 degrees Celsius warming globally, not just on lands; a separate IPCC climate report set to come out in September will focus on oceans.)

“The temperature over land is warming at twice the speed of the global average,” Verchot told BuzzFeed News. To date, average surface air temperatures over land have risen about 1.5 degrees Celsius compared to pre-industrial levels. This is not a measure of total warming — excluding the warming of air temperatures over the oceans that cover most of the planet. The Paris climate agreement seeks to limit global warming to no more than 2 degrees Celsius, with an ideal limit of 1.5 degrees, to stave off the worst impacts.

Amid a population boom, humans have expanded their consumption of food, timber, energy, and more. To do this, people have used more and more land and freshwater resources. The result, scientists say, is a spike in emissions.

Most greenhouse gas emissions stem from the burning of fossil fuels. However, agriculture, forestry, and other types of land use, from 2007 and 2016, accounted for about 23% of total net human-related greenhouse gas emissions, per the report. For now, thanks to plants working overtime in natural landscapes free of human development, land cover areas still pull more emissions out of the atmosphere than they release into it.

The initial effects of climate change, however, are already showing themselves.

“Climate change, including increases in frequency and intensity of extremes, has adversely impacted food security and terrestrial ecosystems as well as contributed to desertification and land degradation in many regions,” per the summary report for policymakers.

While warming has resulted in more frequent, intense, and longer heat waves in most land areas, specific regions like much of Africa and South America have also been hit by worsening droughts. More frequent and intense dust storms, linked to climate-changes, are hurting people’s health in regions such as the Arabian Peninsula and Central Asia. The impacts on crops are more mixed, with lower-latitude regions experiencing some declines in maize and wheat crops whereas higher-latitude regions have seen some crop yield increases.

The report isn’t all doom and gloom, offering many recommendations for cutting emissions through changes in land use and eating habits.

“One of the important findings of our work is that there are a lot of actions that we can take now,” said Pamela McElwee, a study author, on a press call. “We don’t have to wait for some sort of new technological innovation.” Some examples include reducing deforestation and cutting down on food waste.

“Diets present major opportunities for reducing greenhouse gases,” study author Cynthia Rosenzweig said on the same call for reporters, “because diets that are rich in plant-based foods emit lower greenhouse gas emissions than diets that are very heavy in red meat consumption.”

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