# Contents * toc {: toc} ## Idea ## **The Copenhagen Diagnosis**, authored by a [team of climate scientists](http://www.copenhagendiagnosis.com/authors.html), was intended to serve as an interim evaluation of the evolving science before the 5th [[IPCC]] report, which is not due for completion until 2013. It was also intended to as a handbook of science updates that supplemented the IPCC AR4 in time for the meeting in Copenhagen in December 2009. * [The Copenhagen Diagnosis](http://www.copenhagendiagnosis.com/), 2009. ## Executive Summary ## Here is the [executive summary](http://www.copenhagendiagnosis.com/download/Copenhagen_Diagnosis_ES_English.pdf): +-- {: .quote} The most significant recent climate change findings are: **Surging greenhouse gas emissions:** Global carbon dioxide emissions from fossil fuels in 2008 were 40% higher than those in 1990. Even if global emission rates are stabilized at present-day levels, just 20 more years of emissions would give a 25% probability that warming exceeds 2 °C, even with zero emissions after 2030. Every year of delayed action increase the chances of exceeding 2 °C warming. **Recent global temperatures demonstrate human-based warming:** Over the past 25 years temperatures have increased at a rate of 0.19 °C per decade, in very good agreement with predictions based on greenhouse gas increases. Even over the past ten years, despite a decrease in solar forcing, the trend continues to be one of warming. Natural, short-term fluctuations are occurring as usual but there have been no significant changes in the underlying warming trend. **Acceleration of melting of ice-sheets, glaciers and ice-caps:** A wide array of satellite and ice measurements now demonstrate beyond doubt that both the Greenland and Antarctic ice-sheets are losing mass at an increasing rate. Melting of glaciers and ice-caps in other parts of the world has also accelerated since 1990. **Rapid Arctic sea-ice decline:** Summer-time melting of Arctic sea-ice has accelerated far beyond the expectations of climate models. The area of summertime sea-ice during 2007-2009 was about 40% less than the average prediction from IPCC AR4 climate models. **Current sea-level rise underestimates:** Satellites show great global average sea-level rise (3.4 mm/yr over the past 15 years) to be 80% above past IPCC predictions. This acceleration in sea-level rise is consistent with a doubling in contribution from melting of glaciers, ice caps and the Greenland and West- Antarctic ice-sheets. **Sea-level prediction revised:** By 2100, global sea-level is likely to rise at least twice as much as projected by Working Group 1 of the IPCC AR4, for unmitigated emissions it may well exceed 1 meter. The upper limit has been estimated as 2 meters sea-level rise by 2100. Sea-level will continue to rise for centuries after global temperature have been stabilized and several meters of sea level rise must be expected over the next few centuries. **Delay in action risks irreversible damage:** Several vulnerable elements in the climate system (e.g. continental ice-sheets, Amazon rainforest, West African monsoon and others) could be pushed towards abrupt or irreversible change if warming continues in a business-as-usual way throughout this century. The risk of transgressing critical thresholds (“[[tipping points]]”) increase strongly with ongoing climate change. Thus waiting for higher levels of scientific certainty could mean that some tipping points will be crossed before they are recognized. **The turning point must come soon:** If global warming is to be limited to a maximum of 2 °C above preindustrial values, global emissions need to peak between 2015 and 2020 and then decline rapidly. To stabilize climate, a decarbonized global society – with near-zero emissions of CO2 and other long-lived greenhouse gases – need to be reached well within this century. More specifically, the average annual per-capita emissions will have to shrink to well under 1 metric ton CO2 by 2050. This is 80-95% below the per-capita emissions in developed nations in 2000. =-- category:climate,reports [[!redirects The Copenhagen diagnosis]]