The report says that warming of the climate system is ‘unequivocal’ and points to observation data as proof. It adds that stabilising the concentration of greenhouse gases (GHGs) would require them to peak – after the anticipated, short-term at least, further increase – and then decline.
About three-quarters of the stabilisation scenarios point to the prime role of energy supply and energy efficiency. Hydropower is one of the proscribed key mitigation technologies in the energy sector cited in the report, the others including nuclear power and an array of other renewables plus carbon storage and combined heat and power (CHP).
While noting the potential for mitigation from proven technologies, the report cautions that ‘without substantial invest flows and effective technology transfer, it may be difficult to achieve emission reduction at a significant scale. Mobilising financing of incremental costs of low-carbon technologies is important’.
In describing the forecasts of changing hydrology, the report said its studies had ‘high confidence’ that, by mid-century, annual river runoff and water availability were likely to increase in high latitudes and some tropical wet areas but decrease in some dry regions in the mid-latitudes and tropics.
The IPCC said there was also ‘high confidence’ that there would be reduced water resources in semi-arid areas, such as the Mediterranean basin, western US, southern Africa and North east Brazil. The only reference to a rise in specific regional risk for hydropower the report pointed to the Mediterranean basin.
With regard to North America, the report says: ‘Warming in western mountains is projected to cause decreased snowpack, more winter flooding, and reduced summer flows, exacerbating competition for over-allocated water resources.’
While the report mentions hydropower specifically in a few instances, especially as a mitigation technology to help stabilise, it also mentions in many areas the broad disruptive effects to food and health and security from the change in climate patterns. The increase in hydrological risk presents a broader challenge to water resources, and the roles of dams and reservoirs in irrigation, water supplies and flood management.
The “Synthesis Report” constitutes the Fourth Assessment report from the IPCC. Earlier this year, from February to May, it released three forerunner reports dealing with the physical science basis for its finds, the impacts, adaptation and vulnerability issues, and mitigation prospects, respectively.
The latest report says scientist’ predictions view as ‘very likely’ there being increased frequency of hot extremes, heat waves and heavy precipitation. In addition, the predictions are that it is ‘very likely’ precipitation will increase in high latitudes and ‘likely’ fall in most subtropical land regions, continuing observed recent trends.
The latest report is the ‘decisive effort to integrate and compact this wealth of information’, and also bring in some parts of material in full Working Group studies that were ‘over and above’ the previous summaries for policymakers, said the IPCC.
Next month there will be the next Conference of the Parties (CoP), in Bali, that is held to debate and advance plans on what to do about IPCC findings. The event was rescheduled to enable the report to be produced and form the basis for discussions, and the document was finally signed-off by the dozens of international scientists involved during a week-long meeting in Valencia, Spain.
In a statement, the IPCC said: ‘The report will constitute the core source of factual information about climate change’ for policymakers to ‘base their political action upon in the coming years’.
