Climate change deniers have had a field day over the past few years, pointing almost gleefully to the fact that there has been no discernible increase in average global surface temperatures since 1998, despite greenhouse gas emissions ratcheting up new records year after year. Hence, they argued, the entire “thesis” of global warming had been exposed as pure bunkum since there now appeared to be no linear relationship between increasing emissions and rising temperatures.
The UN's Intergovernmental Panel on Climate Change (IPCC) was also at a low ebb, following the discovery of errors in its Fourth Assessment (2007), notably an outlandish claim, based on no scientific evidence whatever, that Himalayan glaciers would melt away as soon as 2037.
But the IPCC has hit back with a powerful punch. In the first part of its Fifth Assessment, published last week and dealing with the physical science basis of climate change, it concludes that the evidence for global warming is "unequivocal" and argues convincingly that the general trend needs to be observed over a 30-year period, rather than a mere decade and a half.
The report also suggests that a higher proportion of the excess heat in recent years may have been taken up by the oceans (which already absorb more than 90 per cent of the excess energy generated by global warming) in ways not yet fully understood. But the longer-term trend is clear, with the last three decades progressively warmer than any period since 1850.
Since the scientists are virtually certain that humans are to blame for pumping greenhouse gases into the atmosphere at levels “unprecedented in at least the last 800,000 years”, we are directly implicated in warming the atmosphere and oceans, melting glaciers, declining Arctic summer sea ice, rising sea levels and changes in some climate extremes.
It is up to us, therefore, to set the course for “substantial and sustained reductions” in emissions so that future generations are not condemned to endure the worst consequences of climate change. This can only be done if world leaders seriously apply themselves to the monumental task of concluding a meaningful international agreement before the end of 2015.
Further reports from the IPCC's Fifth Assessment will feed into this process, perhaps even steeling the nerves of politicians in facing down those with a vested interest in the status quo. Neither can the recession be used as an excuse for inaction; the cost of doing nothing now will be immeasurably more severe in its impact than anything we have suffered as a result of the banking crisis.
Amid warnings that Ireland, as a temperate country, could face an influx of “climate refugees” from hotter parts of the world as the warming trend continues, the Government must set realistic targets for cutting Ireland’s emissions as a contribution to dealing with the greatest challenge facing humanity.