Climate change is happening. There have already been enough changes in the Earth’s systems that it seems highly unlikely we will be able to go back to levels of CO2, global temperatures, or sea level rise that would cause no impact to societies around the globe. Therefore, we will need to think of ways to minimize the impacts. Sustainability is the way to think going forward, because it suggests that we need to balance humans’ well-being and the Earth’s (since it sustains us). We want to ensure the continued health of everyone and everything on the planet.
Sustainability suggests that we will have to make changes to our (human) practices in order to counteract the manmade aspects of climate change. As the levels of CO2 continue to rise, the temperature on Earth will continue to rise, the oceans will continue to become more acidic and plants and animals will change or die out depending on their ability to migrate. These climate changes that are ongoing are leading us down an unsustainable path. So we must change. Whether those changes act to mitigate and/or to adapt to the new climate system, we cannot continue on as before.
The sustainable practices that have been suggested range from long term to short term solutions. Some of them are untested and the consequences of trying them are unknown (eg geoengineering). Some suggestions would act in a longer period of time, reducing emissions of CO2 to varying degrees in order to attempt to stabilize the change at an acceptable level. This might, in turn, affect the climate on earth as the upward trend in CO2 is leveled off or even decreased. This will change what is needed to sustain life on Earth.