The risks to people and the planet from climate change are growing, and the world is still poorly prepared to manage those risks even though it has learned more about how to adapt, a scientific report from the United Nations' climate panel said on Monday.
The report, issued by the Intergovernmental Panel on Climate Change (IPCC), observed that, in recent decades, changes in climate have caused impacts on natural and human systems "on all continents and across the oceans".
These range from melting glaciers to falling wheat and maize yields, food price spikes, deaths from heat waves, and harsh humanitarian consequences from climate-linked disasters.
"We live in an era of man-made climate change. In many cases, we are not prepared for the climate-related risks that we already face," said Vicente Barros, co-chair of Working Group II, a team of hundreds of scientists who produced the report. "Investments in better preparation can pay dividends both for the present and for the future," he added in a statement.
People who are marginalised socially, economically and politically are most vulnerable to climate change, including those who suffer discrimination due to gender, class, ethnicity, age and disability, the report said.
"Climate-related hazards affect poor people's lives directly through impacts on livelihoods, reductions in crop yields, or destruction of homes, and indirectly through, for example, increased food prices and food insecurity," the report said.
At the same time, it outlined the advances that have been made in climate adaptation responses since the last major IPCC report in 2007, noting that experience is accumulating across regions, in the public and private sector and within communities.
The report gives examples of measures that are already being taken, including early warning systems, better water management, mangrove planting on coastlines, hardier crop varieties, protection for utilities and other public infrastructure, and planning for sea-level rise.
Chris Field, co-chair of Working Group II, said tackling climate challenges "creatively" can make adaptation "an important way to help build a more vibrant world in the near-term and beyond".
But the report also identified constraints to putting adaptation into practice. They include limited financial and human resources, poor coordination, uncertainties about climate impacts, differing perceptions of risks, and insufficient tools to monitor how well policies work.
The report pointed to "a gap between global adaptation needs and the funds available for adaptation", adding that there is a need for better assessment of adaptation costs, funding and investment.
The study is part of the IPCC's fifth assessment of the scientific knowledge on climate change. A first report, released in September, looked at the physical science of climate change; a further one, due out in April, will examine efforts to mitigate climate change.
Lead authors of the report told Thomson Reuters Foundation it is now clear the risks from climate change will continue to rise in the next two decades or so, whether or not efforts are stepped up to cut the greenhouse gas emissions that are warming the Earth.
"The projections into the future are looking a lot more alarming than they were before ... things are looking bleaker," said Saleemul Huq, director of the Bangladesh-based International Centre for Climate Change and Development and a senior fellow with the London-based International Institute for Environment and Development.
For example, local floods and droughts might damage crop harvests in Asia or Russia which then push up international food prices, sparking riots in places like Egypt, Huq noted.
"There is a new kind of global vulnerability, which is inherently unpredictable...when things happen in several places they can add up to much more than two and two being four," he said.
Some of the numbers included in an earlier draft summary of the report, prepared by scientists for policy makers to approve at a meeting in Japan last week, were removed from the final version - mainly because they were subject to a high level of uncertainty, or susceptible to misinterpretation, experts at the negotiations said.
The official summary warned, nonetheless, that a bigger proportion of the global population will experience water scarcity and river floods as temperatures rise this century.
A large fraction of animal, bird and fish species face higher extinction risk, and coastal systems and low-lying areas will experience worsening submergence, coastal flooding and erosion due to sea-level rise.
More people, especially the poorest, will be displaced from their homes by extreme weather and longer-term climate shifts, the report predicted.
Without adaptation, wheat, rice and maize production will decline in tropical and temperate regions where local temperatures rise 2 degrees Celsius or more above levels late last century, though some places may benefit, the report said.
And climate change is expected to lead to increases in ill-health this century in many regions, especially in poor developing countries.
Global economic impacts are hard to estimate, but annual losses could range from 0.2 percent to 2 percent of income if the world's temperatures rise around 2 degrees Celsius, the report said. Overall, climate change is expected to make poverty worse.
"Throughout the 21st century, climate-change impacts are projected to slow down economic growth, make poverty reduction more difficult, further erode food security, and prolong existing and create new poverty traps, the latter particularly in urban areas and emerging hotspots of hunger," the report noted.
AID GROUPS WORRIED
Humanitarian and development agencies said the IPCC's findings are worrying for the vulnerable people they assist.
"From the Red Cross perspective, we are really concerned about what this report tells us about the potential long-term humanitarian consequences," said Maarten van Aalst, director of the Red Cross/Red Crescent Climate Centre. "If we go on with the 'business as usual' scenario (for emissions), which we are very much on...then we are indeed going to those very high temperature scenarios."
Huq said a key message from the report was that the world can more or less manage the threats from a 2-degree Celsius warmer world, which will mainly hit the poor.
But if global temperature rise reaches 4 degrees, which many scientists predict will happen unless more mitigation occurs, then "it becomes a totally different picture".
"Even the rich will be affected ... and they will not escape anymore, so hopefully that will lead to a collective realisation we need to act now, and the window for opportunity is the next few decades to reduce emissions while at the same time enhancing adaptation," Huq said.
The report warned that greater rates and magnitude of climate change increase the likelihood of "exceeding adaptation limits", when the actions needed to avoid intolerable risks are not possible or available.
That might include scenarios such as small Pacific nations being forced to abandon some of their islands due to rising seas, storms and saltwater intrusion.
"With high levels of warming that result from continued growth in greenhouse gas emissions, risks will be challenging to manage, and even serious, sustained investments in adaptation will face limits," Working Group II co-chair Field said.
Aid group Oxfam called on governments to respond by massively increasing investment in adaptation, and agreeing to cut emissions.
"This report shows that we face a major reversal in the fight against hunger," said Tim Gore, Oxfam's head of policy for food and climate change.
"Without urgent action on adaptation and emissions reduction, the goal of ensuring every person has enough to eat may be lost forever. Political leaders reading this report should ask themselves whether this will be the generation to let that happen."