Climate Change & Extreme Weather Notes

Exam Review and Logistics

Exam review slides will be posted five to ten days before the exam.
The last problem set is due Thursday.
The last couple of questions involve an online tool for sale horizon projections, which will be mapped.
The quantitative parts of the problem set have been covered.
The lecture will cover additional material and introduce extreme events.
Research from our research group from last chemo emissions maps with Matt LabCo

The lecture addresses the calculation of sea level rise resulting from ice melt from Greenland and Antarctica, discussing nonlinearities in the response of ice sheets to warming.
Updated slides have been posted to detail the algebra involved in these calculations.

Adding New Water: Melting ice sheets add new water to the ocean, distinct from thermal expansion.
This added water is fresh and has a different density than ocean water.
Volume Change: The primary question is how the addition of this freshwater changes the height of the ocean.

The surface area of the ocean remains constant despite the added height.
The added mass of ice is equivalent to an added mass of seawater, without changing the global ocean's density.

If the added seawater mass equals the added ice mass: m{seawater} = m{ice}
Since mass equals volume times density: V{seawater} \times \rho{seawater} = m_{ice}
Rearranging gives the volume of seawater added: V{seawater} = \frac{m{ice}}{\rho_{seawater}}
For ice volume calculations: m{ice} = V{ice} \times \rho_{ice}

Seawater and ice densities are well-known, allowing for estimations of sea level rise from ice loss.
Calculations can be made from both mass and volume of ice lost using the density equation.

Historically, about half of the sea level rise is attributed to thermal expansion.
Greenland and Antarctica contribute about half of the rise from melting land ice.
Mountain glaciers contribute the other half, historically matching the combined contribution of Greenland and Antarctica.

Despite being smaller than the ice sheets of Greenland and Antarctica, mountain glaciers significantly contribute to sea level rise due to melting.
There has been an acceleration in mass loss from mountain glaciers.
Exponential loss of mass
Example: The Menahawk picture has retreated in total, right, more than half a kilometer just, you know, over about a decade. *Not all glaciers are retreating; some high-elevation glaciers are growing where it is still cold enough for ice accumulation.
- As warming progresses, the loss of mountain glaciers is accelerating globally.

Coastal erosion, groundwater withdrawal, and tectonic processes also impact local sea level rise.
Groundwater Withdrawal: Groundwater withdrawal and substance causes lower land to the level of the sea. Agriculture has been causing a lot of groundwater withdrawal.
Local sea level trends can differ from global trends due to these factors.
Atmospheric Pressure:
- Low atmospheric pressure, such as in tropical storms, causes the sea surface height to rise.
- In the long term, areas with lower atmospheric pressure experience a higher sea surface.
- Atmospheric pressure changes contribute to sea level rise heterogeneously, reflecting gyre circulation patterns.
- The magnitude of these contributions is in the millimeter range, smaller than those from ice melt.

Under a very high emission scenario (SSP5-8.5), thermal expansion remains the largest projected change, contributing about a third of a meter over the next century.
Non glaciers contribute more than the Antarctic or Greenland ice sheets, although there's uncertainty in the Antarctic ice sheet projections.
Thermal expansion is not spatially uniform, reflecting variations in heat content.
Vertical land motion, whether from tectonic processes or groundwater withdrawal, affects the impact of sea level rise locally.
Conservative estimates for Antarctica and Greenland may not account for potential destabilization of these ice sheets.
Warming from emissions over the next century has a long lifetime, potentially causing significant sea level rise on longer time scales.

Familiarize yourself with the sea level prediction tool and projected sea level rise in different locations.
Connect projected sea level rise with cumulative emissions.
Predict median sea level rise for a location like Redwood City in 2100, considering net-zero emissions by 2040.

The lecture transitions to discussing extreme events, including detection and future projections.
The focus is on understanding how changes in the mean climate affect extreme events.
Extreme events often drive the most significant experiences and stresses in the climate system.

The IPCC assessment of hot, wet, and dry events visualizes changes with dot icons.
The frequency of an event that occurred once every fifty years is now happening about five times as often with two degree Celsius of global warming.
The intensification of heat relates to the Clausius-Clapeyron relation (approximately 7% increase in water vapor in saturation per degree Celsius of warming).
The increase in frequency is smaller for a one-in-ten-year event compared to a one-in-fifty-year event.
There is a linear increase in intensity for extreme events.

Wet Event: Much smaller increase in frequency for the one in ten year event for precipitation.

Research group focuses on the interface between climate dynamics and climate impacts to understand phenomena that stress people, society, organisms, and ecosystems.
Interested in what causes these phenomena and how global warming affects them.
Work includes extreme events (heat waves, floods, droughts, tornadoes, tropical cyclones) and their impacts.
Economic impacts are considered, with attention to various industries.

Explore the financial losses from disasters, focusing on non-tropical cyclone flooding events. Lots of different impacts and effects on different economies.
**Methodology: General regression
*Focus on the scale and pace of losses from flooding extreme events. The flooding that was not from Tropical Cyclones

*Wettest condition is responsible for the most damages.