Final answer:
Under a Business As Usual scenario with high greenhouse gas emissions, climate models estimate global temperatures could increase by 2°F to 11.5°F by 2100. These increases are based on various scenarios and assume continued emissions. Further warming is expected to occur on land and particularly in the Arctic.
Step-by-step explanation:
If we continue with a Business As Usual (BAU) approach, leading to high greenhouse gas emissions, climate models forecast substantial increases in global temperatures. Estimates suggest that average global temperatures could rise by about 2°F to 11.5°F by the year 2100. These predictions are backed by various climate models and take into account different scenarios of greenhouse gas emissions. Emissions scenarios like the IPCC's A2 scenario show significant increases relative to the 1961-1990 averages. Additionally, even if we stop adding CO₂ now, temperatures are still expected to rise due to the oceans absorbing the current CO₂ excess.
Under the high emission BAU scenario, radiative forcing could be around 2.5 W/m², corresponding to a temperature increase of approximately 2°C. Moreover, research has indicated that the warming effect will be more pronounced on land than on the oceans, and even more so in the Arctic. Current projections also indicate that by 2100, global average temperature is expected to warm at least twice as much as it has during the last 100 years. It is important to note that these predictions are based on current models, which can vary due to different assumptions made about future emissions and their impacts on global temperature.