Chemical toxicity
Synthetic chemicals that persist in the environment are linked to health risks
The past century has witnessed an explosive proliferation of synthetic chemistry. Humanity has synthesized over 100 million compounds not found in nature, with up to 350,000 currently in commercial use. Many of these, like PFAS, microplastics, and some pesticides, do not fully biodegrade and will persist and accumulate in soil, water, and living tissues. Studies have identified both correlations and causal links between a wide range of toxic exposures and concerning health outcomes, many of which have risen sharply in recent decades.
| Category | Pesticides | PFAS | Microplastics | Heavy metals |
|---|---|---|---|---|
| Fertility |
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| Cancer |
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| Neurodegeneration |
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| Cardiovascular disease |
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| Immune-system dysfunction |
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| Inflammatory bowel disease |
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| Mood disorders |
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| Insect declines |
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Source: Deep Science Ventures, based on top 50 "best-matched" papers on Pubmed.
Climate change
While 1% of the planet is currently uninhabitable due to heat, within 50 years these scorching conditions could expand to cover areas where a third of the world's population currently lives.
In 2070, the Earth is expected to be at least 2°C warmer than before we started burning fossil fuels. At that level of warming, extreme heat, drought, shifting rainfall patterns and other effects will increasingly threaten crop yields, food security, and the livelihoods of billions of people who depend on agriculture.
This world map of average temperatures highlights in black those areas that are too hot for human habitation today, and in black shading those areas that will be too hot for humans by the year 2070. Such areas will include some of the most populated regions of the globe.
Tipping points may take us to a point of no return
Greenhouse gas emissions may push the Earth past key tipping points that trigger self-reinforcing feedbacks and drive the planet toward a long-term "Hothouse Earth" state. In this scenario, even if human emissions decline, natural processes (like methane emissions from permafrost and albedo loss from ice sheet melt) could sustain higher global temperatures for centuries.
Tipping Elements — Big Risks in the Earth System | PIK (2022)
The geographical distribution of global and regional tipping elements, color-coded according to the best estimate for their temperature thresholds, beyond which the element would likely be 'tipped'. Figure designed at PIK (under cc-by licence), based on Armstrong McKay et al., Science (2022).