The latest report from the U.N. climate panel, in which scientists said they were more certain of human influence on global warming than ever before, reinforces the need to boost support for the world's poorest communities who are already experiencing severe climate impacts, international aid experts said on Friday.
Thomas Stocker, co-chair of the working group that produced the report, told journalists that the rising sea-levels, higher temperatures and precipitation shifts outlined by the Intergovernmental Panel on Climate Change (IPCC) clearly demonstrate that "climate change challenges the two primary resources of humans and ecosystems - land and water."
"In short, it threatens our planet, our only home," added the Swiss climate scientist.
Many humanitarian and development groups said the report confirmed what they are witnessing on the ground in their work to help impoverished people cope with worsening climate-related disasters and longer-term stresses.
"This report gives further scientific backing to what our partner organisations around the world have been telling us: the climate is changing, and not in a good way. Droughts, floods and erratic weather are ruining crops and damaging communities," said Paul Cook, advocacy director at Tearfund.
Maarten van Aalst, director of the Red Cross Red Crescent Climate Centre, said the report underlined how the world has no choice but to adapt to climate change. "For the next few decades, whatever we do to cut greenhouse gas emissions will not stop the climate changing, uncertainties about rainfall and weather extremes heightening, or risks rising," said van Aalst, who is also a lead author for another forthcoming IPCC report on climate impacts, adaptation and vulnerability.
The summary of the physical science report, released on Friday with the full version to follow, said scientists are virtually certain there will be more frequent hot - and fewer cold - temperature extremes over most land areas as global temperatures increase. It is also very likely heat waves will be more frequent and last longer, they said.
The contrast in precipitation between wet and dry regions, and between wet and dry seasons, will increase, although there may be regional exceptions, according to the document for policy makers, which was approved by 110 governments.
Monsoon precipitation is likely to intensify, and the monsoon season to lengthen in many regions, it said. Droughts are likely to be worse and happen more often by the late 21st century, it added.
It also said global sea levels could rise between 26 and 82 cm (10 to 32 inches) by late this century, driven by melting ice and an expansion of water as it warms, in a threat to coastal settlements. That range is higher than the 18-59 cm estimated in 2007.
Sven Harmeling, climate change advocacy coordinator for the aid group CARE, said the global climate is already reversing efforts to tackle poverty, and the lack of concerted action "is fast becoming the greatest social injustice of our time".
He urged more support to protect vulnerable people from disasters and to help them adapt to climate shifts - from farmers in Niger who can no longer rear livestock to poor families in Pakistan who have been battered by monsoon floods several years in a row.
In the future, "there might be some regions where you have a more horrific situation: maybe more droughts and more flooding," he told Thomson Reuters Foundation. "In the longer-term there might be some regions that become uninhabitable."
CHEAPER TO ACT NOW
Aid agencies also emphasised that their worst fears could be avoided if governments, businesses and individuals act on the messages in the IPCC report by cutting greenhouse gas emissions far more deeply and urgently.
"Governments should learn from the mistakes of the global financial crisis where warning signs were ignored and listen to the experts before it is too late," said Tim Gore, head of policy for Oxfam's Grow Campaign. "They must take actions immediately to slash emissions as well as investing in building the resilience of people in poverty so we can move from the current path facing disaster to higher safer ground."
Oxfam warned in a report earlier this week that climate change will leave families caught in a vicious spiral of falling incomes, rising food prices and declining quality of food, leading to a devastating impact on the health of millions.
The World Resources Institute pointed to the mounting losses from climate-induced crises. "The costs multiply every day. Droughts disrupt food supplies. Rising seas displace populations. Hurricanes and typhoons wreak havoc on communities worldwide," said WRI president Andrew Steer.
"Climate change is not only profoundly unjust - hurting especially the poor, who have done least to cause it - it is also undermining prospects for future economic growth," he said. He noted that the costs of action on climate change "are modest, and are dwarfed by the costs of inaction".
Other development experts flagged up the rising price paid by people in richer countries across Europe, North America and elsewhere, who are also experiencing more extreme weather events.
"Because of political inertia and powerful vested interests that have dominated media narratives for decades, they are less aware of the links between these impacts and their carbon emissions," said Saleemul Huq, senior fellow at the International Institute for Environment and Development (IIED), who is also a coordinating lead author for the IPCC report on climate adaptation. "Climate change affects us all and we must tackle it together. The time has come for global solidarity."
IIED director Camilla Toulmin stressed that while climate models are still unable to predict impacts at the local level, "everybody is vulnerable in some way".
"This uncertainty about local impacts, coupled with the certainty that impacts will come, is a stark warning that everyone needs to get ready. Citizens and business leaders worldwide need to press governments to act, both at home and on the international stage," she said in a statement.