Guide 02 · Impacts
What is a hotter world already doing?
Short answer: more and fiercer heatwaves, heavier downpours, longer droughts, shrinking ice and rising seas. Those hit food, water, health and homes, and they land hardest on the people and places that did least to cause them. Every extra tenth of a degree makes it worse.
Heat
Records are falling every year
A warmer average shifts the whole range of weather, so extremes that were once rare become routine.
How often a once-in-50-years heatwave strikes
Times as often as in the pre-industrial climate, for a land heat extreme that used to happen once in 50 years. IPCC AR6 WG1, Summary for Policymakers, Figure SPM.6.
Each year since 1940 vs pre-industrial
- Paris limit (1.5°C)
- Yearly average (ERA5)
Source: Copernicus ERA5 ·
Ice
The frozen parts of the planet are retreating
Arctic sea ice, mountain glaciers and the Greenland and Antarctic ice sheets are all losing mass. Less white ice means more dark ocean and land soaking up sunlight, which speeds up warming further.
Arctic sea ice at its yearly low
-12.1% per decadeShow the data as a table
| Year | Minimum (M km²) |
|---|---|
| 2025 | 4.54 |
| 2024 | 4.25 |
| 2023 | 4.24 |
| 2022 | 4.69 |
| 2021 | 4.76 |
| 2020 | 3.79 |
| 2019 | 4.17 |
| 2018 | 4.63 |
| 2017 | 4.64 |
| 2016 | 4.15 |
| 2015 | 4.39 |
| 2014 | 4.99 |
| 2013 | 5.04 |
| 2012 | 3.34 |
| 2011 | 4.33 |
| 2010 | 4.59 |
| 2009 | 5.05 |
| 2008 | 4.55 |
| 2007 | 4.15 |
| 2006 | 5.75 |
| 2005 | 5.31 |
| 2004 | 5.77 |
| 2003 | 5.97 |
| 2002 | 5.63 |
| 2001 | 6.57 |
| 2000 | 5.94 |
| 1999 | 5.68 |
| 1998 | 6.29 |
| 1997 | 6.60 |
| 1996 | 7.15 |
| 1995 | 6.01 |
| 1994 | 6.93 |
| 1993 | 6.16 |
| 1992 | 7.16 |
| 1991 | 6.26 |
| 1990 | 6.01 |
| 1989 | 6.89 |
| 1988 | 7.05 |
| 1987 | 6.89 |
| 1986 | 7.12 |
| 1985 | 6.49 |
| 1984 | 6.40 |
| 1983 | 7.20 |
| 1982 | 7.16 |
| 1981 | 6.90 |
| 1980 | 7.53 |
| 1979 | 6.90 |
Source: NSIDC Sea Ice Index v4 ·
Oceans
Rising, warming and turning more acidic
The ocean has absorbed about 90% of the extra heat trapped since the 1970s and about a quarter of our CO₂. That has spared the air, at a cost: warmer water expands and fuels stronger storms, and dissolved CO₂ makes seawater more acidic.
Show the data as a table
| Year | mm vs 1993 |
|---|---|
| 2024 | +101 |
| 2023 | +98 |
| 2022 | +92 |
| 2021 | +90 |
| 2020 | +85 |
| 2019 | +82 |
| 2018 | +76 |
| 2017 | +73 |
| 2016 | +73 |
| 2015 | +69 |
| 2014 | +61 |
| 2013 | +58 |
| 2012 | +55 |
| 2011 | +45 |
| 2010 | +47 |
| 2009 | +45 |
| 2008 | +42 |
| 2007 | +38 |
| 2006 | +38 |
| 2005 | +35 |
| 2004 | +32 |
| 2003 | +30 |
| 2002 | +27 |
| 2001 | +25 |
| 2000 | +20 |
| 1999 | +16 |
| 1998 | +17 |
| 1997 | +18 |
| 1996 | +14 |
| 1995 | +10 |
| 1994 | +5 |
| 1993 | 0 |
Source: NOAA Laboratory for Satellite Altimetry ·
People
Those least responsible are hit first
Climate change multiplies existing risks: crop failures, water shortages, disease, displacement and conflict. Wealth, health and geography decide who can adapt.
Why every fraction matters
1.5°C versus 2°C
Half a degree sounds small. In the IPCC's assessment it is the difference between damaging and devastating for many systems.
| Impact | At 1.5°C | At 2°C |
|---|---|---|
| Warm-water coral reefs | Decline by 70–90% | More than 99% lost |
| Ice-free Arctic summer | About once a century | At least once a decade |
| Insects losing over half their range | 6% of species | 18% of species |
| Plants losing over half their range | 8% of species | 16% of species |
| Sea-level rise by 2100 | About 10 cm less than at 2°C | Up to 10 million more people exposed |
| Global marine fishery catch | Falls ~1.5 million tonnes | Falls over 3 million tonnes |
IPCC Special Report on Global Warming of 1.5°C (2018), Summary for Policymakers, sections B.2–B.4.
Questions people ask
What are the main effects of climate change?
More frequent and intense heatwaves, heavier downpours and floods in many regions, longer droughts in others, rising seas, shrinking ice and glaciers, more acidic oceans and coral bleaching. Those knock on to food, water, health and economies, and hit the poorest hardest.
How much has sea level risen?
About 20 cm since 1900 (IPCC), and the rate is speeding up. Satellites have measured 103 mm of rise since 1993, now about 3.7 mm a year. Seas will keep rising for centuries as the ocean warms and ice sheets melt.
Is Arctic sea ice disappearing?
It is shrinking fast. The late-summer minimum has fallen by about 12.1% per decade since 1979 compared with the 1981–2010 average. The Arctic could see its first practically ice-free September before 2050 even if emissions fall.
What is the difference between 1.5°C and 2°C?
A lot. Compared with 1.5°C, at 2°C coral reefs decline by over 99% rather than 70–90%, an ice-free Arctic summer becomes about once a decade rather than once a century, and around 10 million more people are exposed to sea-level rise by 2100 (IPCC Special Report on 1.5°C).
Who is most affected by climate change?
People who have done least to cause it. The IPCC estimates 3.3 to 3.6 billion people live in places highly vulnerable to climate change, especially in Africa, South Asia, small island states and the Arctic, and among the poor, elderly and outdoor workers everywhere.