Question

What are the major IPCC projections for climate changes in the 21 st century?

Short answer

According to IPCC, 21st-century projections include a likely rise in global temperatures, an increase in sea levels, significant changes in CO2 concentrations, and substantial alterations to global ecosystems.

Step-by-step solution

Understand the IPCC

The Intergovernmental Panel on Climate Change (IPCC) is an international body that evaluates climate change science. The IPCC's reports cover the scientific, technical, and socio-economic knowledge about climate change, its impacts, and future risks, also proposing mitigative strategies.

Temperature Rise Projections

The IPCC projects that global temperatures are very likely to increase over the course of the 21st century, with a possible increase of 1.5 to 4.5 degrees Celsius by 2100, depending greatly on human activities and particular response strategies.

Sea Level Rise Projections

The IPCC also suggests that sea levels may rise due to thermal expansion of the oceans and melting of ice on land. The projected increase is between 0.3 and 1 meter by 2100, but a rise beyond this is possible and will continue for centuries because of the inertia within the climate system.

Greenhouse Gas Emissions Projections

Regarding greenhouse gas emissions, the IPCC has produced different possible scenarios. Most of them show us that if we continue on the current path, CO2 concentrations could be about double the pre-industrial level by the end of the 21st century.

Changes to Ecosystems

The IPCC also forecasts substantial changes to global ecosystems. The predictions indicate that, if the global average temperature exceeds preindustrial levels by 1.5 to 2.5 Celsius degrees, approximately 20-30% of plant and animal species risk extinction.