Nature Reports Climate Change: April 2010

A new view on sea level rise
Stefan Rahmstorf

In its 2007 report1, the Intergovernmental Panel on Climate Change (IPCC) projected a global sea level rise of 18 to 59 centimetres from 1990 to the 2090s, plus an unspecified amount that could come from changes in the large ice sheets covering Greenland and Antarctica.
But the physical climate models used by the IPCC have some limitations, prompting the search for alternative approaches to estimating sea level rise. New semi-empirical approaches are based on the idea that the rate of sea level rise is proportional to the amount of global warming — the warmer it gets, the faster ice melts — and they use past sea level and temperature data to quantify this effect.

Over the course of the twentieth century, the rate of sea level rise has roughly tripled in response to 0.8 °C global warming2. Since the beginning of satellite measurements, sea level has risen about 80 per cent faster, at 3.4 millimetres per year3, than the average IPCC model projection of 1.9 millimetres per year. The difference between the semi-empirical estimates and the model-based estimates of the IPCC can be attributed largely to the response of continental ice to greenhouse warming. The IPCC range assumes a near-zero net contribution of the Greenland and Antarctic ice sheets to future sea level rise, on the basis that Antarctica is expected to gain mass from an increase in snowfall. Observations show, however, that both ice sheets have been losing mass at an accelerating rate over the past two decades4.

A number of recent studies taking the semi-empirical approach have predicted much higher sea level rise for the twenty-first century than the IPCC, exceeding one metre if greenhouse gas emissions continue to escalate (Fig. 1). These new results have found wide recognition in the scientific community, as recent broad-based assessments show5–7. The question is: how plausible are the new estimates?

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امروز مقاله ای را از نیچر اینجا می خواندم در مورد اینکه پیش بینی های انجام شده در مورد بالا آمدن سطح دریاها ممکن است بیش از آن چیزی باشد که تا کنون پیش بینی شده است. در این مقاله اشاره شده است که در گزارش سال 2007 آی پی سی سی پیش بینی شده است که طی هشتاد سال آینده این افزایش حدود 18 تا 59 سانتی متر خواهد بود در حالی که ممکن است فرآیند با سرعت بیشتری رخ بدهد و سطح دریاها تا حدود 120 سانتی متر افزایش پیدا کند.

در نمودار زیر مقایسه چند مدل پیش بینی افزایش سطح دریاها ارائه شده است.