Every continent has been affected by climate change, and the risks of not curbing greenhouse gas emissions that cause it will grow in the coming years, according to a comprehensive United Nations report.
The latest iteration of the U.N. Intergovernmental Panel on Climate Change expanded on previous findings, delving into ocean acidification, food production and threats posed by extreme weather events linked to growing concentrations of greenhouse gases in the atmosphere.
"[C]hanges in climate have caused impacts on natural and human systems on all continents and across the oceans," said the report, which was released Sunday.
Species, both onshore and marine, have migrated — humans may follow. Crop yields have taken a hit. The Arctic is to warm at a faster rate than expected. Recent climate-related weather events underscore human vulnerabilities to a changing climate. Food insecurity will hit the poor the hardest.
"Increasing magnitudes of warming increase the likelihood of severe, pervasive and irreversible impacts," said the report, which builds on a previous version that said humans are driving climate change largely by burning fossil fuels.
But local communities and governments are responding, the report noted, by developing climate adaptation plans. In North America, that's taken the form of long-term investments in making energy and other infrastructure more resilient to climate-induced weather -- the Obama administration, for example, is conducting a sweeping review of energy infrastructure due by Jan. 31.
"The report highlights the widespread and substantial observed impacts of climate change, and its growing adverse effects on livelihoods, ecosystems, economies, and human health," said John Holdren, the top White House science and technology adviser. "Importantly, it also concludes that effective adaptation measures can help build a more resilient global society in the near term and beyond."
Some of those adaptation measures include updated flood mapping that would highlight the risk of living in certain areas prone to climate-related weather events, maintain natural -- such as wetlands -- and engineered barriers to reduce exposure to risk, planting drought-resistant crops and using water-saving technology.
Secretary of State John Kerry said the report served as a call to action for countries, which are looking to strike an agreement at climate talks in Paris next year to cut emissions enough by 2020 to prevent global temperatures from rising 2 degrees Celsius by the end of the century.
"Read this report and you can't deny the reality: Unless we act dramatically and quickly, science tells us our climate and our way of life are literally in jeopardy. Denial of the science is malpractice," Kerry said.
Hitting that global climate goal is looking increasingly tenuous — most climate scientists say current projections will leave that mark unrealized unless action is taken, and fast. And as the world warms, dealing with the effects of climate change will become increasingly difficult, the U.N. report warned.
The cornerstones of President Obama's climate agenda are twin rules restricting carbon emissions at new and existing power plants. On Friday, the White House also revealed a strategy for cutting emissions of methane, a short-lived, but potent, greenhouse gas.
Those types of actions need to become more widespread to shield communities from the effects of climate change, the report said.
While there is variability in the impact climate change will have on differing systems across the world, the report agreed some of its effects include: Death, ill health, injury and home destruction in low-lying and island communities vulnerable to storms; health risks in urban centers due to increased flooding; mortality risks during periods of extreme heat and drought; and threats to rural livelihoods because of lack of irrigation water and poor crop yields.
"Climate change is projected to amplify existing climate-related risks and create new risks for natural and human systems. Some of these risks will be limited to a particular sector or region, and others will have cascading effects," the report said.