In 1992, the Union of Concerned Scientists including the majority of living science Nobel laureates, penned the "World Scientists' Warning to Humanity"calling on humankind to curtail environmental destruction and warning that "a great change in our stewardship of the Earth and the life on it is required, if vast human misery is to be avoided." They showed that humans were on a collision course with the natural world. They proclaimed that fundamental changes were urgently needed to avoid the consequences our present course would bring.
The authors of the 1992 declaration feared that humanity was pushing Earth's ecosystems beyond their capacities to support the web of life. They described how we are fast approaching many of the limits of what the biosphere can tolerate without substantial and irreversible harm. They implored that we cut greenhouse gas (GHG) emissions and phase out fossil fuels, reduce deforestation, and reverse the trend of collapsing biodiversity.
In 2017, humanity was given a second notice. Over 15,000 scientists signed a new and even more urgently worded letter which warned that "To prevent widespread misery and catastrophic biodiversity loss, humanity must practice a more environmentally sustainable alternative to business as usual. This prescription was well articulated by the world's leading scientists 25 years ago, but in most respects, we have not heeded their warning. Soon it will be too late to shift course away from our failing trajectory, and time is running out. We must recognize, in our day-to-day lives and in our governing institutions, that Earth with all its life is our only home."
At the end of 2018, the UN Secretary General warned us:
This is our final notice - we must act now.