4. The Cryosphere
Ice. Other than being simultaneously beautiful and terrifying, it has a huge impact on not only studies of the origins of climate change, but also the effects of it manifesting. 44 percent of the world’s population lives on coastlines, and rising sea level due to anthropogenic causes is already underway. Our guest for this chapter of the IPCC report was Tad Pfeffer. He went into detail to explain and integrate knowledge of Cryosphere observations into the bigger picture of climate change.
The most important aspect to this information is how melting continental ice sheets contributes to sea level rise, and how we contribute to the melting of these ice sheets.
Ice. Other than being simultaneously beautiful and terrifying, it has a huge impact on not only studies of the origins of climate change, but also the effects of it manifesting. 44 percent of the world’s population lives on coastlines, and rising sea level due to anthropogenic causes is already underway. Our guest for this chapter of the IPCC report was Tad Pfeffer. He went into detail to explain and integrate knowledge of Cryosphere observations into the bigger picture of climate change.
The most important aspect of this information is how melting continental ice sheets contributes to sea level rise, and how we contribute to the melting of these ice sheets. The IPCC summarized a few key statements from the overview of the report about ice. From the second slide presented by Pfeffer (those claims are italicized), I will explain in greater depth each of these claims.
Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent (high confidence). The Greenland and Antarctic Ice sheets have been losing mass at an incredible rate. These sheets are more worrying than sea ice because they will contribute to seal level rise and they alter regional salinity and atmospheric circulation.
From 1998 to 2012, it appears we have lost nearly 3,000Gt of ice on the Greenland Ice sheet, and the Antarctic has lost nearly 2,000Gt of ice since that time. Additionally, the rate at which we lose the ice is rising rapidly, and the mean snow cover in the Northern Hemisphere has decreased significantly over the last years culminating to a low point in June around 2010.
Even permafrost has risen in temperature, creating more of an active layer. This active layer supports plant life, but there is CO2 stored in the permafrost from plants that have been frozen in a live state. The more that permafrost melts, the more CO2 it releases into the air.
The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence). Over the period 1901 to 2010, global mean sea level rose by 0.19 [0.17 to 0.21] m. This was mentioned briefly in the last entry, but is important enough to be reiterated. This graph below shows the relation between year and sea level rise and the results do not look good, unless you are a fish, and even then you have a whole other host of problems.
It is very likely that the Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises. Global glacier volume will further decrease. Global mean sea level will continue to rise during the 21st century. Under all RCP scenarios, the rate of sea level rise will very likely exceed that observed during 1971 to 2010 due to increased ocean warming and increased loss of mass from glaciers and ice sheets.
Glaciers are contributing to seal level rise as well. Many glaciers distributed throughout the world have lost anywhere from 1Gt to 100 Gt per year. Their lines of ablation are retreating sometimes more drastically than researchers expect. This map shows the mass balance of glaciers as of last year, and a trend of shrinking is clear from the loss of these glaciers.
It is clear that the cryosphere is straight up melting. It has a large impact on sea level rise. Whether it is glaciers, continental ice sheets, or river ice causing damage to homes, something needs to be done. It has been said the IPCC is alarmist, but I have taken the journey myself to look at this data, and I see what they see- the writing on the wall. Even if these models are generous, we can see rates of ablation increasing, and we can see ice calving off in large amounts. The planet is changing, and the evidence is in the ice.