In this talk I[ am going to describe the extent to which observed changes in climate can be attributed to natural and anthropogenic factors.] with particular reference to the oceans.
I will present the greater evidence available now compared to AR4 that human-induced changes are occurring right across the climate system, including atmosphere, oceans and cryosphere.
I will also discuss how increased understanding allows us to better quantify the anthropogenic and natural forcings. While a perspective of at least 30 years is needed to provide a robust assessment of attribution of climate changes.
And then discuss how the major headlines from the Second Assessment report to the Fifth assessment report have changed.
mean percentage change in projected 169 maximum catch potential (MCP) of 280 Exclusive Economic Zones (EEZs) and mean percentage 170 change in projected revenues of 192 fishing nations in the 2050s relative to the level in the 2000s 171 under RCP 8.5 scenario
- Use multi-model ensemble
The destruction of coral reefs directly threatens the physical boundaries and security of the Pacific islands, and poses serious food security risks to islands that rely on agriculture and fisheries as their main food sources. Because reefs form a natural, physical barrier that protects the coastline from severe weather events, their destruction, combined with rising sea levels, causes sea water to infiltrate farmland as well as lead to coastal erosion.
Generally, estimated economic stresses due to climate change project losses of USD 63 billion per year starting in 2010. This influence will increase by more than 100 percent to USD 157 billion each year by 2030 (Fundacion DATA Internacional, 2010). Average Annual Losses (AAL) as a percentage of GDP is much higher in SIDS compared with the global average as shown by Chart 3 above. Asset replacement charges arise out of inaction in arranging for climate change impacts. The total value of infrastructure, buildings, and cash crops considered at some level of risk in the Pacific is estimated at over US$111 billion. In the Pacific Region, the asset replacement cost is on average 4 times greater than the GDP (in 2013), for some countries such as Timor-Leste the ratio of asset replacement cost is 14 times their GDP. (UN-OHRLLS, 2015).
Explain the figures …
Changing Ocean, Marine Ecosystems, and Dependent Communities
Multiple lines of robust
evidence support the
conclusion that many
aspects of the climate
system have changed.
Warming in the climate system is unequivocal
The oceans have warmed.
Human influence on the
climate system is clear
Changes in key physical and biogeochemical properties and processes, including the deep ocean and
relevant ocean regions, modes of variability, teleconnections and their feedbacks on the climate system
A global view of oxygen loss over the past 50
years, largely fueled by warming, yields 2%
loss, but much greater regional losses.
Multiple mechanisms drive oxygen
loss in the open ocean and
generate climate feedbacks
Schmidtko et al. 2017; Levin, 2018
Changes to resource ratios are usually ignored
Changes to resource ratios shape ecosystems
(long history in ecology)
Key example: Fe/N ratio shaping success (or
not) of nitrogen fixing algae
Ward et al. (2013; Limnol. Oceanogr.)
Resource ratios are changing in the
north Pacific (and perhaps elsewhere …)
Kim et al. (2014; Science)
We need to think about relative changes and the impacts on the productivity and ecosystems
Catches and livelihood
Loss of USD 10 billion in revenue per year, 35% more than loss of catches.
Lam et al. (2016). Sci. Rep.
Projected impacts on fish stocks and
Human communities (wellbeing)
Countries that are highly dependent on seafood-sourced micro-nutrient (e.g., omega-3-
fatty acid, zinc) are projected to have largest decrease in catches under climate change.
Golden et al. (2016) Nature.
Reefs at risk in the western pacific. Reefs at risk revisited.
Burke et al 2011
Worst affected SIDS by the consequences of
climate change by share GDP: Pacific Region.
Chapter 5: Outline
2. Changing Oceans and Biodiversity
3. Changing Marine Ecosystem Services and Human
4. Solutions and Governance