Wk12: Responses to climate change

What does the IPCC (Intergovernmental Panel on Climate Change) do? 

Assesses peer‑reviewed climate science to inform governments; summarises physical science, impacts/vulnerability, and mitigation.

How much has the planet warmed since 1850–1900? 

~1.1°C of human‑caused warming (IPCC 2023).

Why is current CO₂ rise unprecedented? 

CO₂ levels now exceed any time in the last 800,000+ years, rising far faster than natural cycles.

What are climate scenarios (SSPs)? 

Shared Socioeconomic Pathways modelling future emissions: SSP1‑1.9 (very low), SSP1‑2.6 (low), SSP2‑4.5 (medium), SSP3‑7.0 (high), SSP5‑8.5 (very high).

What is a carbon budget?

 The total CO₂ that can be emitted while keeping warming below a target (e.g., 1.5°C or 2°C).

Remaining carbon budget for 1.5°C (>50% chance) 

~500 Gt CO₂ from 2020; shrinking rapidly with current emissions.

Key IPCC finding on vulnerability 

3.3–3.6 billion people live in highly climate‑vulnerable contexts, despite contributing least to emissions.

Observed climate impacts (IPCC)

 Increases in heat extremes, heavy rainfall, and agricultural/ecological drought across most regions.

Why limiting warming gets harder over time? 

Delayed action steepens required mitigation curves; requires massive negative emissions later.

What are Nationally Determined Contributions (NDCs)? 

Country‑level climate pledges under the Paris Agreement; currently insufficient for 1.5–2°C.

Paris Agreement goal 

Limit warming to “well below 2°C” and pursue efforts to stay below 1.5°C.

IPCC assessment of current NDCs 

On track to exceed 1.5°C this century; makes limiting warming below 2°C much harder without stronger action.

What is the UNFCCC? 

1992 treaty establishing global cooperation on climate change; parent framework for Kyoto and Paris.

What is the Kyoto Protocol? 

1997 treaty with binding emissions targets for developed countries; introduced carbon markets and offsets.

What is the Green Climate Fund? 

UNFCCC fund supporting mitigation and adaptation in developing countries; goal of US$100B/year (not yet met).

Global fossil fuel trend (IEA) 

Projected to peak before 2030, but not decline fast enough to meet 1.5–2°C pathways.

Why renewables alone aren’t enough yet? 

Renewable growth is strong, but global energy demand is rising faster, especially in Asia and Africa.

Historical emissions responsibility 

Europe + USA responsible for the largest share of cumulative CO₂ since 1750; central to climate justice debates.

What is a “just transition”? 

Ensuring climate action is fair, protects workers/communities, and addresses inequalities in responsibility and impact.

Australia’s current climate targets 

43% emissions reduction below 2005 levels by 2030; net zero by 2050; renewables ~39% of electricity (2023).