Question

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

Short answer

The IPCC projects significant climate changes in the 21st century: a continued increase in global mean surface temperature, changes to precipitation affecting various resources, a faster rate of sea-level rise than the past 40 years, and an increase in extreme weather events such as heat waves and heavy precipitation. It is however important to note that these changes can hugely vary depending on the rate of greenhouse gas emissions.

Step-by-step solution

Understand the role of IPCC

The IPCC gathers and assesses scientific information relevant to climate change to provide decision-makers with regular assessments of the scientific basis of climate change, its impacts, and potential future risks. It also puts forward adaptation and mitigation options.

Gather information on IPCC's projections

IPCC’s Fifth Assessment Report (AR5), provides a range of key future climate projections. The main points to take note of include: an increase in global temperature, changes in precipitation, sea-level rise, and increased frequency and intensity of extreme weather events

Summarize the key points

The IPCC projects that the global mean surface temperature will continue to rise - over the 21st century, very likely is expected to exceed 1.5°C with projections ranging from 0.3°C to 4.8°C depending on the rate of greenhouse gas emissions. Sea levels will continue to rise this century at a faster rate than we have experienced over the past 40 years. Changes to precipitation patterns are expected, affecting water resources, food production and risk of flooding. The number of extremely hot days are expected to increase, leading to a higher risk of heat-related health issues and bushfires. The occurrence of heavy precipitation leading to flooding is also expected to increase in many regions.

Key concepts

Global Temperature Increase

One of the major projections by the IPCC is the increase in global temperature. Over the 21st century, we are very likely to see a significant rise in global mean surface temperature. This increase ranges from 0.3°C to possibly as much as 4.8°C. The extent of this change largely depends on how much greenhouse gas emissions we manage to control.

The rise in global temperatures is not just a number in studies; it can have real-world impacts. As temperatures increase, we may encounter more heatwaves, which can affect agriculture and water supply. Heatwaves can also lead to health problems like heatstroke and worsen respiratory issues. It's crucial for us to understand and mitigate these changes to protect our environment and health.

Sea-Level Rise

Sea-level rise is another critical projection made by the IPCC, and it's expected to occur at a faster rate than we have seen in recent decades. This rise is caused primarily by two factors:

• The melting of ice sheets and glaciers, which adds more water to the oceans.
• Thermal expansion, which is the increase in ocean volume as water warms up.

This has several implications for coastal areas worldwide. Many regions face the risk of increased flooding, loss of habitat for plants and animals, and potential damage to human infrastructure.

Communities living in low-lying areas or islands are particularly vulnerable. The proactive measures such as building sea defenses, planning for migration, and enabling ecosystems to adapt, can significantly mitigate these risks.

Precipitation Changes

Changes in precipitation patterns are another critical area of focus in IPCC's climate projections. As the climate warms, it affects how, when, and where precipitation falls. Some regions may experience more rainfall, while others might suffer longer droughts.

Increased rainfall can lead to flooding, affecting agriculture, water resources, and human settlements. On the other hand, areas experiencing reduced rainfall face the challenges of drought, which can reduce water availability and affect crop yield.

• This variance in precipitation patterns can significantly influence regional ecosystems and biodiversity.
• Changes in precipitation also impact energy generation, especially in hydropower-dependent regions.

Understanding these changes allows us to better plan resource management and develop strategies to adapt to new environmental conditions.

Extreme Weather Events

The IPCC's projections highlight an increase in the frequency and intensity of extreme weather events such as hurricanes, tornadoes, and heatwaves. These events are becoming more prevalent due to the changing climate.

For example, warmer sea surface temperatures can lead to more intense hurricanes, as they gain energy from the heat. Similarly, increased atmospheric moisture can result in heavy precipitation, contributing to severe flooding.

• Extreme weather also disrupts infrastructure, affects food supply, and can lead to economic losses.
• It poses challenges to emergency services and requires more robust disaster preparedness and adaptation strategies.

Recognizing the potential increase in these events helps communities and policymakers prioritize resilience measures and ensure that societies can cope with these extreme conditions.