Final answer:
It is true that by the end of the 21st century, large portions of Earth's surface may experience new climates due to significant global temperature rises, according to climate models. These changes are anticipated to result in loss of biodiversity and shifts in species distributions, as well as a range of impacts on human populations, including rising sea levels and increased weather extremes.
Step-by-step explanation:
By the end of the 21st century, large portions of Earth's surface may indeed experience climates not found at present. This statement aligns with predictions from climate models which indicate that the mean global surface temperature is likely to rise by 0.3-4.8 degrees C (0.5-8.6 degrees F) before the temperature levels off (IPCC, 2007).
The warming is not uniform, with more significant increases over land and in the Arctic compared to oceans, due to the different heat absorption capacities. These temperature alterations will likely lead to shifts in species distributions and loss of biodiversity, as both marine and terrestrial species migrate poleward to track suitable climates, with marine species moving much faster than terrestrial ones.
Human-induced climate change presents a distinct scenario compared to past natural changes, like ice ages and glacial periods. Human activities such as deforestation and land conversion into agriculture have created an 'obstacle course' for species attempting to migrate in response to changing conditions. These transformations, along with increased greenhouse gas emissions, are already leading to shifts in natural habitats, more extreme weather events, shifts in food production patterns, and a rise in sea levels, among other consequences.
Moreover, forecasts reveal potential changes that could impact human civilization, including the melting of polar ice caps which would raise ocean levels, potentially making some coastal areas uninhabitable and causing 'climate refugees' as people are displaced from their homes. Thus, the contemporary pace and nature of global warming may indeed forge environments and climates that human history has not yet witnessed.