Attributes of our modern world, including over- and inequitable consumption, have contributed
to the increase in non-communicable diseases (NCDs) and their unfair social distribution. These
same social attributes, along with continuing growth in the global population, have led to
increased atmospheric concentrations of greenhouse gases (GHGs), particularly CO 2 , methane,
and nitrous oxide, and to climate change. This combined concentration of GHGs means that
Earth's average surface temperature will rise by at least 2°C by 2050, with a further total
warming by 2100 to within the range of 1.8°C–4.0°C. As the temperature of the planet rises,
there are, and will be, more frequent and severe floods, droughts, storms, and heat waves.

These changes to Earth's biophysical system will exacerbate and extend the rates and ranges of
many diseases and overall poor health among all populations. And without a lessening of
background rates of diseases, the multiplier effects of climate change on health outcomes will
greatly exacerbate existing health inequities between and within countries, which poses a
major additional challenge to international development. One major, although conservative,
estimation suggested that the extent of climate change that had already occurred by the year
2000 was directly responsible for the loss of at least 5.5 million disability adjusted life years
(DALYs) in that year and that the poorest countries and populations experienced the greatest
proportion of the disease burden. That assessment related only to diarrhea, malaria, injuries
from coastal and inland floods or landslides, and malnutrition.

The most common NCDs (heart disease, stroke, cancer, type 2 diabetes, and respiratory
diseases) accounted for 60% of the 58 million global annual deaths in 2004. The current and
projected growth in mortality from NCDs is mainly in low- and middle-income countries.
The mental health impacts of climate change are unequally distributed with certain groups
disproportionately affected depending on factors such as socioeconomic status, gender and
age. However, it is clear that climate change affects many of the social determinants that are
already leading to massive mental health burdens globally. A 2021 WHO survey of 95 countries
found that only 9 have thus far included mental health and psychosocial support in their
national health and climate change plans.