Climate change caused 400,000 deaths in 2010 from hunger and communicable diseases, including diarrhoea and malaria, hitting children in developing countries the hardest, according to the 2012 Climate Vulnerability Monitor. Carbon-intensive energy use was responsible for over 4.5 million deaths, most due to indoor smoke from dirty stoves and air pollution, it said.
Climate impacts - including floods, droughts, sea-level rise and reduced labour productivity - are estimated to have cut the world's gross domestic product (GDP) by a net 0.8 percent in 2010. And the harmful effects of the "carbon economy" - such as oil spills and damage to biodiversity, fisheries and forests - equalled 0.7 percent of lost GDP, the report said.
"The explosive increase in heat expected over the coming decades will only lead to a corresponding escalation in these costs, increasingly holding back growth as emissions go unabated and efforts to support the worst-affected communities fail to meet the challenges at hand," the report warned.
Losses are expected to increase rapidly, it noted, reaching 3.2 percent of GDP and 6 million deaths per year by 2030.
"A combined climate-carbon crisis is estimated to claim 100 million lives between now and the end of the next decade," it said.
The study, commissioned by a forum of 20 nations vulnerable to the effects of climate change, highlighted how poor countries are already suffering the most - an injustice that is set to continue.
A huge 98 percent of all deaths linked with climate change in 2010 occurred in developing states. And least-developed countries sacrificed on average over 7 percent of GDP in that year due to climate-related damages and lack of access to clean energy - a figure expected to rise to more than 11 percent by 2030.
'RAMIFICATIONS OF INACTION'
Bangladeshi Prime Minister Sheikh Hasina said a 1 degree Celsius rise in the planet's temperature since pre-industrial times is costing her country 3 to 4 percent of GDP annually, with a fall in grain production accounting for around half.
"After 17 years of international (climate) negotiations, we are still without any meaningful agreement or action to reduce global warming. As a climate vulnerable country, every day we see and feel the ramifications of that inaction," she said in a statement launching the report.
José María Figueres, former president of Costa Rica and a trustee of DARA, the research organisation that produced the study, said a world struggling to eliminate poverty and tackle financial woes "simply cannot afford to part with more growth".
"With the investment required to solve climate change already far below the estimated costs of inaction, no doubt remains as to the path worth taking," he said.
The cost of shifting the world economy to a low-carbon footing is around 0.5 percent of GDP for the current decade, although it rises for subsequent decades, according to the report. That would include curbing greenhouse gas emissions aggressively and using much more renewable energy.
In addition, the study calculates that developing countries require at least $150 billion a year to adapt to climate change today, increasing to an annual minimum of $1 trillion by 2030. While these top many other estimates, they are lower than the expected damages, and so "adapting to climate change is very likely a cost-effective investment in almost all cases and should be central to any climate change policy", the report argued.
TOO HOT TO WORK
Matthew McKinnon, head of DARA's climate vulnerability initiative and editor of the report, told AlertNet his team had used the latest science and research to produce a more immediate and comprehensive assessment of the costs of climate change than other widely cited international studies.
For example, the DARA study counts the brake on labour productivity from the growing number of hotter days, which is a major hidden cost of climate change, but one that is rarely considered, he said.
During research for a country case study in the report, villagers in southern Ghana had talked about how teachers were struggling to do their job properly because of an increase in excessive heat, McKinnon said.
The monitor, the second to be issued, calculates and compares the climate vulnerability of 184 countries across four areas - environmental disasters, habitat change, health impact and industry stress - using 34 indicators of the effects of climate change and high-carbon policies.
The 20 countries in the forum - mostly African, Asian, Latin American and small island states - are keen to pursue low-carbon development in order to boost their economic productivity and reduce their reliance on costly imported fuel, McKinnon said.
Costa Rica, for instance, aims to be carbon neutral by 2021, and Bangladesh has committed never to exceed the average per-capita emissions of developing countries.
But the worrying fact is that most of the world is still heading in the opposite direction, using ever more oil, coal and gas to fuel economic growth, McKinnon warned.
"That reality must change," he said. "The consequences are already here and in excess of the costs to solve the problem. So get going now, because the window to solve this is fast closing."