The latest report from the United Nations’ Intergovernmental Panel on Climate Change says the effects of a warming world are not in the far-off future, but are happening right now.
And they’re taking a toll on humans as well as natural systems. Rain and snow patterns are changing. Glaciers are melting. Water supplies appear to be shrinking, and animals on land and in the oceans are shifting their ranges.
“There’s clear evidence of climate impacts today,” said Michael Prather, a UC Irvine climate researcher and lead chapter author for the U.N. panel. “Some are really obvious, some are more subtle. The issue is what the future looks like.”
Climate change appears to be reducing crop yields in some places, and extreme weather – droughts, floods, cyclones – is exposing humanity to disruptions in food production and perhaps even increased illness or death.
While some effects of climate change may be irreversible, the report has a modest silver lining: People are beginning to adapt to the changes, with governments in many places, including North America, factoring climate change into long-range planning.
But the risks to people and nature are high, especially at the higher end of estimates of potential warming in the decades to come.
Today, the effects of a changing climate are interwoven with a variety of other concerns, and might not yet be keenly perceived by many, Prather said.
“People’s response is much more tempered by other forces,” Prather said. “I don’t think climate change is a major force today. But it should be anticipated by our children as one of the major forces. I think in 50 years, it’s going to be a different issue.”
The climate-change report is the most recent in a series that began with last year’s assessment of climate trends, which pronounced climate change “unequivocal” and pegged the likelihood that it was driven mainly by human activity at 95 to 100 percent.
The most recent report, released after a meeting in Yokohama, Japan, focuses on the effects of climate change and our vulnerability to them, as well as actions we can take to adapt.
Scientists at the meeting, who are part of the U.N. panel’s Working Group II, hammered out a summary for policymakers.
More than 300 authors and editors from 70 countries prepared the report, relying on more than 400 contributing authors and more than 1,700 expert and government reviewers.
The newest reports are the international science group’s fifth climate assessment since the first was issued in 1990.
The report also gauges likely future effects in different parts of the world, though it says the effects of climate change are being felt “on all continents and across the oceans.”
Drought, heat waves, dwindling snow pack and crashing fisheries are already familiar to Californians, and the report says such effects are likely to become worse as the Earth grows ever warmer.
With a high degree of confidence, the report says that the U.S. West Coast will see powerful effects on marine ecosystems, snow and ice – much of California’s water supply depends on a shrinking Sierra Nevada snow pack – as well as big effects on drought and flooding.
In North America as a whole, climate change should have a minor effect on wildfire, but major effects on land-based ecosystems as well as snow, ice and glaciers.
Extreme temperatures could cause more deaths in the decades ahead, while extreme weather such as cyclones could in some cases increase flooding.
An expected rise in sea levels, meanwhile, means storm drains and outfalls might need to be updated to continue functioning properly.
Bottom line: Increasingly precise data generated by scientists is allowing a far more acute assessment of the potential effects of climate change.
“It’s not just ecosystems and species, but people,” Prather said. “So many things are happening at so many different levels, and in so many places. People are working on it, and people are interested in doing it. It’s sort of like this wealth of more and more information to think about, and that’s acted on.”
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