climate change as an example of a major Earth systems issue

global temperatures in 2024

average surface temperature in 2024 was warmest on record - 1.28 degrees C above 20th century baseline

Arctic amplification

Near-surface Arctic air temperatures are increasing by a factor of 2 to 3 relative to the rest of the global

why is arctic amplification particularly concerning?

1. Albedo feedbacks

2. Habitat loss

3. Atmospheric teleconnections

during La Nina

strong easterly winds blow across the equatorial Pacific and a result, warm water piles up in western Pacific

ENSO

a major shift in currents in Pacific ocean every 2-10 years

El Nino years

these easterly winds weaken or are replaced by westerlies that drive this surface warm water eastwards towards south America. This releases heat back to the atmosphere

why do global air temperatures increase during El Nino years

heat is released from the oceans to the atmosphere

retreat of glaciers

Glaciers retreat when their terminus does not extend as far down-valley as it previously did.

temperature and glacier

Glaciers may retreat when their ice melts more quickly than snowfall can accumulate and form new glacial ice. Higher temperature and less snowfall have been causing many glaciers around the world to retreat recently.

oxygen isotopic analysis

proxy for temperature at which the ice was deposited

proxy records

preserved characteristics that act as substitutes for direct meteorological measurements

the more negative the values

the less heavy the isotope

sunspot cycle

11 year cycle

more sunspots…

increase solar radiation reaching earth

could solar variability be responsible for recent warming

no

models

only models that include anthropogenic forcing climate can reproduce the observed warming