Chapter 2 Flashcards
CO2 levels are higher than at any time in the?
Last 2 million years
Anthropogenic CO2 is identifiable how?
On average lighter than those naturally present in the atmosphere.
Global surface temperatures have increased faster since 1970 than in any other 50 year period over the…?
Last 2,000 years
Some aerosols have cooling effects, but this peaked in?
2020
For the greenhouse effect, which GHG is most important?
H2O
After H2O, which are the most important GHGs for contributions to warming?
CO2, CH4, N2O
How much of the atmosphere is H2O?
1-4%
CO2 from fossil fuels contributes what % of total GHG emissions?
Two thirds of
Pre-industrial CO2 versus current?
0.028% versus 0.041%
GHG with longest life
PFCs - 50,000 years
Global warming Potential (GWP) of the different GHGs over 100 years?
CO2 - 1
CH4 - 28
N2O - 273
HFCs - -14,600
PFCs - 7,380
SF7 - 25,200
NF3 - 17,400
Lifetimes of different GHGs
CO2 - no figure can be given as varies
CH4 - 12 years
N2O - 109 years
HFCs - 228 years
PFCs - 50,000 years
SF6 - 3,200 years
NF3 - 569 years
What % of currently emitted CO2 is rapidly taken up by oceans and the biosphere?
50%
What is enhanced rock weathering?
Hybrid strategy which involves grinding rocks artificially so that the reaction between silicate rocks and CO2 is accelerated, being stored in the deep ocean
CO2 budget left according to Indicators of Global Climate Change 2022 report for 1.5C?
50% chance: 250bn tonnes (6 years of current emissions); but only 150bn tonnes for a 67% chance
Which UK act requires governments sets a 5 year limit / carbon budget on the UK’s emissions to achieve 2050 net zero?
UK Climate Change Act 2008. Budgets set by independent adviser, the Climate Change Committee (CCC) based on latest science and impact on UK’s cost competitiveness, fuel poverty, fiscal balance, and national/international responsibilities.
What is the planetary boundary for climate change?
CO2 of 350 ppm (0.035%), within which natural processes are able to self-regulate and absorb deviations
How many of how many planetary boundaries have been exceeded?
6 of 9
What is solar radiation modification?
Spraying of cooling sulphate aerosols into the atmosphere to reflect solar radiation away from Earth. However, concerns this disrupts water cycle and is linked to weakened monsoons and the melting of the Tibetan glaciers. Also air pollution health concerns.
What is radiative forcing?
Net increase in energy within the Earth and atmosphere system
What is the name given the climate scenarios scientists use to simulate different plaidable scenarios of emissions?
Representative Concentratioj Pathways (RCPs). E.g. RCP8.5 means 8.5W per m2 of radiative forcing by 2100.
2023 temperature stats:
What was average temperature? And temperature rise?
All days had global temp above XC?
How many % of days were 1.5C or more warmer?
What was hottest month in recorded history?
14.98C, 1.48C
1C
50%
July 2023
Additionally, hottest seven month period on record occurred from June to December 2023, including warmest ever June, July, and august
What is the scope of the RCPs?
Representative Concentration Pathways only determine level of GHG emissions and associated temperature rises. They do not envisage economic, technological, or political developments to get there.
Which scenarios have been developed to reflect different challenges in the way of abatement or adaptation and to describe how global society may evolve under these assumptions?
Shared Socio-Economic Pathways (SSEP) with distinct assumptions around economic growth, population, inequality, literacy, technological change, and urbanisation. The outputs are climate policies and emissions reductions under the different scenarios.
What is the lowest possible scenario used for climate modelling and what is it a blend of?
SSP and RCP1-1.9 -> 1.5C
Based on the SSP scenarios, what conclusion did the IPCC’s 2021 come to?
That global temperatures will continue to rise to 2050 under all scenarios
What is the best current estimate of climate sensitivity?
3C every time concentration of CO2 doubles, but range is 2.5-4C
What can you say about clouds?
Complex as both blanket and reflective effect. Depends on altitude and thickness of cloud. Difficult to model. Latest science expects net warming effect.
Land versus sea warming?
Land areas have warmed about twice as fast as the oceans