First report on UK climate impact

By David Shukman
Science Editor, BBC News

image captionThe last year saw low levels in some English reservoirs

Climate change this century poses both risks and opportunities, according to the first comprehensive government assessment of its type.

The report warns that flooding, heatwaves and water shortages could become more likely.

But benefits could include new shipping lanes through the Arctic, fewer cold-related deaths in winter and higher crop yields.

The findings come in the Climate Change Risk Assessment.

This 2,000-page document has been produced by the Department for Environment, Food and Rural Affairs (Defra).

It forms part of the government's strategy for coping with global warming.

The research was carried out over the past three years and involved studying the possible impacts in 11 key areas including agriculture, flooding and transport.

The assessments rely on multiple scenarios based on computer modelling of the future climate.

The authors admit that there are large uncertainties leading to a wide range of possible results.

image captionIncreased damage from flooding could lead to bills running into the billions

The relatively small size of the UK means that modelling at a regional and local level remains a serious challenge.

A further limitation is that the studies share the assumption that no sectors of the economy will make any attempt to adapt to future conditions.

This is designed to provide a "baseline" for the assessment so that it is easier to demonstrate the risks unless action is taken.

However it is acknowledged that many bodies are already responding in different ways.

Headlines for possible negative outcomes, assuming nothing is done in preparation, include:

  • Hotter summers leading to between 580-5900 deaths above the average per year by the 2050s.
  • Water shortages in the north, south and east of England, especially the Thames Valley area by the 2080s.
  • Increased damage from flooding could cost between £2.1bn-£12bn by the 2080s.

The report's positive findings include:

  • The melting of Arctic sea ice opening shorter shipping routes to Asia.
  • Milder winters leading to 3,900-24,000 fewer premature deaths by the 2050s, significantly more than those forecast to die as a result of hot weather.
  • Wheat yields to increase by 40-140% and sugar beet yields by 20-70% because of longer growing seasons by the 2050s.

Such widely-varied outcomes may lead to the criticism that the results are too vague to be useful for policy makers, businesses and local authorities.

image captionThe impact on transport is a major consideration

All the scenarios rely on computer models of the future climate and therefore inherently involve uncertainties.

The report itself acknowledges that the sea-level in London could rise later this century by anything between 30cm and 190cm.

"We do not know," the document says, "how fast greenhouse gas emissions will rise, how great the cooling effects are of other atmospheric pollutants or how quickly the ice caps may melt."

One of those involved in the report, defending the reliance on models, told me: "They're the best we've got, they're all we've got."

One aim of the work is to raise awareness of the scale of possible changes and to encourage key organisations to plan ahead.

Environment Secretary Caroline Spelman said of the report: "It shows what life could be like if we stopped our preparations now, and the consequences such a decision would mean for our economic stability."

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