1) The climate system is accumulating energy due to increased greenhouse gas concentrations from human activities like burning fossil fuels. 2) Over 90% of this increased energy is being absorbed by warming oceans. 3) Future climate change impacts, like global temperature rise and sea level rise, will depend on how much human greenhouse gas emissions are reduced. Ambitious mitigation could keep temperature rise below 1.5°C, while business as usual scenarios may lead to over 2°C of warming.

1. Physical science basis perspective
IPCC Working Group 1
Valérie Masson-Delmotte

2. The climate system is
accumulating energy
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
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Change in global surface temperature
(Nov-Oct) (°C)
(NOAA, 2015)
>90% increase in
energy : ocean warming

3. Uptake of energy in the climate system is caused
by increase in greenhouse gas concentrations

4. Uptake of energy in the climate system is caused
by increase in greenhouse gas concentrations

5. Carbon dioxide concentrations have increased
by 40% since pre-industrial times
ocean has absorbed 30% of
emitted CO2 causing acidification
15 to 40% of emitted CO2 will
remain in the atmosphere longer
than 1,000 years
Land carbon sink is sensitive to
climate
(Global Carbon Project update planned on Dec 7)

6. Human influence is already detected in warming,
sea level rise, changes in the global water cycle,
and some climate extremes

7. Business as usual
Stabilization
Ambitious mitigation
Future climate will depend on radiative perturbations
(RCP)

8. Global surface temperature change in 2100
is likely to exceed 1.5°C for all scenarios
except for ambitious mitigation
Temperature
Projected temperature change
Precipitation

9. Global mean sea level will continue to rise during
the 21st century and beyond
business
as usual
ambitious
mitigation
Multi-millennial sea level
commitment will depend on
magnitude of global warming
Non uniform

10. Cumulative CO2 emissions (Gt CO2)
Temperature change since 1861-1880 (°C) For warming < 2°C :
2900 Gt CO2 (66%)
-
2000 Gt CO2 (emissions 1870-2011)
=
Remaining: 900 Gt CO2
may be reached in 20-30 years
Cumulative emissions of CO2 will largely
determine global mean surface warming by the
late 21st century and beyond