Lecture 13: Ocean warming

Question 1

sea surface global ocean temperature anomalies

Answer 1

since 1980 considerable warmer seas

Question 2

the sea has been steadily ____ over the past last century

Answer 2

warming

– the last twenty years include 18 of the hottest global Sea surface temperatures ever recorded

Question 3

__% of earths waters occurs in ocean

Answer 3

97% and the mean depth is nearly 4km

Question 4

oceans/air able to absorb more heat

Answer 4

oceans

– reflected in sea surface temperatures but moreso in Ocean Heat Content (OHC)

Question 5

Ocean heat content:

Answer 5

post 1995 we’ve seen steady increase in temps

Question 6

oceans have absorbed ___% of excess heat due to global warming

Answer 6

> 90%

– ocean surface takes a lot

Question 7

if the lower 10km of atmosphere was to absorbs the same quantity of heat the oceans have it would warm by

Answer 7

36 degrees c

Question 8

consequences of a warming ocean, direct:

Answer 8

• rising sea levels (coastal impacts)
• methane gas hydrate dissociation
• deoxygenation (increase temp, decrease waters ability to take in O2)
• melting of sea ice

Question 9

consequences of a warming ocean, indirect: ecological consequences

Answer 9

ecological consequences:

– populations responses: move, adapt, or suffer

Question 10

Consequence of a warming ocean: ecological consequence case study: FISH

Answer 10

• shifting fish on the European Continental Shelf
• ours and marine food webs
• european sea’s warmed particularly rapidly
• bottom-trawl surveys between 1980 and 2008
• some thrive, some abundances decline i.e cod, haddock
• 1DC had little effect, but abundance varied (in 39/50)
• some are moving in response
• commercial fisheries are effected i.e. in haddock and cod

Question 11

Consequence of a warming ocean: ecological consequence case study: FISH. Why did not all fish move?

Answer 11

• can move polewards or deeper to find water
• so dont see strong signal as they are just going deeper, depths are limited though
• fish movements aren’t determined by temp, maybe require certain environments
• those unable to shift they experience ~3.2dc in 21st century

Question 12

generalising across taxa response to climate change

Answer 12

met analysis of many marine taxa we see predictable consistent responses across the taxa
- in shift polewards and phenology

Question 13

generalising across taxa response to climate change: phenology

Answer 13

• phytoplankton respond v quickly

- pelagic animals responding fast

Question 14

consequences of not moving or adapting example

Answer 14

not moving fast enough?

• i.e. bleaching of corals (can’t move)
• warm the seas, corals bleach
• corals have symbiotic algae, is u stress the corals they expel the algae
• bleaching itself is not lethal, but they need time to recover
• recover time is shortening, return time of bleaching events is now only 6 years (not long enough)
• likely to become annual

Question 15

our seas play a key role in maintaining Earths

Answer 15

relatively stable climate, but the energy they have absorbed has caused damages and these will continue
- populations must adapt, move, or suffer

Question 16

2018 ocean heat content:

Answer 16

2018 warmest year for the global oceans