Question

Scientists Say Warming Makes Storms, Like Harvey, Wetter
WASHINGTON (AP) — By the time the rain stops, Harvey will have dumped about 1 million gallons
of water for every man, woman and child in southeastern Texas—a soggy, record-breaking glimpse
of the wet and wild future global warming could bring, scientists say.
While scientists are quick to say climate change didn't cause Harvey and that they haven't
determined yet whether the storm was made worse by global warming, they do note that warmer air
and water mean wetter and possibly more intense hurricanes in the future.
"This is the kind of thing we are going to get more of," said Princeton University climate scientist
Michael Oppenheimer. "This storm should serve as warning."
There's a scientifically accepted method for determining if some wild weather event has the
fingerprints of man-made climate change, and it involves intricate calculations. Those could take
weeks or months to complete, and then even longer to be checked by other scientists.
In general, though, climate scientists agree that future storms will dump much more rain than the
same size storms did in the past.
That's because warmer air holds more water. With every degree Fahrenheit, the atmosphere can hold
and then dump an additional 4 percent of water (7 percent for every degree Celsius), several
scientists say.
Global warming also means warmer seas, and warm water is what fuels hurricanes.
When Harvey moved toward Texas, water in the Gulf of Mexico was nearly 2 degrees (1 degree
Celsius) warmer than normal, said Weather Underground meteorology director Jeff Masters.
Hurricanes need at least 79 degrees F (26 C) as fuel, and water at least that warm ran more than 300
feet (100 meters) deep in the Gulf, according to University of Miami hurricane researcher Brian
McNoldy.
Several studies show that the top 1 percent of the strongest downpours are already happening much
more frequently. Also, calculations done Monday by MIT meteorology professor Kerry Emanuel show
that the drenching received by Rockport, Texas, used to be maybe a once-in-1,800-years event for
that city, but with warmer air holding more water and changes in storm steering currents since 2010, it
is now a once-every-300-years event.
1
Minimizing Human Impact on Earth
There's a lot of debate among climate scientists over what role, if any, global warming may have
played in causing Harvey to stall over Texas, which was a huge factor in the catastrophic flooding. If
the hurricane had moved on like a normal storm, it wouldn't have dumped as much rain in any one
spot.
Harvey stalled because it is sandwiched between two high-pressure fronts that push it in opposite
directions, and those fronts are stuck.
Oppenheimer and some others theorize that there's a connection between melting sea ice in the
Arctic and changes in the jet stream and the weather patterns that make these "blocking fronts" more
common. Others, like Masters, contend it's too early to say.
University of Washington atmospheric scientist Cliff Mass said climate change is simply not powerful
enough to create off-the-chart events like Harvey's rainfall.
"You really can't pin global warming on something this extreme. It has to be natural variability," Mass
said. "It may juice it up slightly but not create this phenomenal anomaly."
"We're breaking one record after another with this thing," Mass said.
Sometime Tuesday or early Wednesday, parts of the Houston region will have broken the nearly
40-year-old U.S. record for the heaviest rainfall from a tropical system—48 inches (120 centimeters),
set by Tropical Storm Amelia in 1978 in Texas, several meteorologists say.
Already 15 trillion gallons (57 trillion liters) of rain have fallen on a large area, and an additional 5
trillion or 6 trillion gallons are forecast by the end of Wednesday, meteorologist Ryan Maue of
Weather Bell Analytics calculates. That's enough water to fill all the NFL and Division 1 college football
stadiums more than 100 times over.
Associated Press text, photo, graphic, audio and/or video material shall not be published, broadcast, rewritten for broadcast or publication or
redistributed directly or indirectly in any medium. Neither these AP materials nor any portion thereof may be stored in a computer except for
personal and non-commercial use. Users may not download or reproduce a substantial portion of the AP material found on this web site. AP will
not be held liable for any delays, inaccuracies, errors or omissions therefrom or in the transmission or delivery of all or any part thereof or for
any damages arising from any of the foregoing.
How have humans contributed to the phenomenon of climate change?
Minimizing Human Impact on Earth
What impact would this information have on communities trying to rebuild or expand in areas
that could experience hurricanes?
What constraints must these communities take into consideration when planning?

Answer 1

Below are concise, evidence-based answers to each question, drawing on the article and standard climate science and planning principles.

1) How have humans contributed to the phenomenon of climate change?
- Burning fossil fuels (coal, oil, natural gas) for energy and transport releases large amounts of CO2; industrial processes and cement production add more greenhouse gases.
- Agriculture, livestock, land-use change and some industrial activities emit methane (CH4) and nitrous oxide (N2O), potent greenhouse gases.
- These added greenhouse gases trap more heat in the atmosphere, raising global temperatures. Warmer air holds more moisture (about 4% more per °F, ~7% per °C), and warmer oceans provide more energy for tropical storms.
- Human activities that alter land cover (deforestation, draining wetlands, coastal development) reduce natural buffers against flooding and can amplify local impacts.

2) What impact would this information have on communities trying to rebuild or expand in areas that could experience hurricanes?
- Higher flood risk: heavier rainfall from storms and higher sea levels mean more frequent and severe flooding, even from storms that might previously have been considered rare.
- Increased infrastructure stress: roads, bridges, drainage, utilities and wastewater systems will face larger loads and more frequent repair needs.
- Economic and insurance impacts: rebuilding costs, higher insurance premiums or loss of insurer capacity, and reduced property values in high-risk zones.
- Public safety and health consequences: greater risk of injury, displacement, mold and waterborne disease, and strain on emergency services.
- Long-term viability questions: repeated, costly rebuilds may make some locations economically or socially unsustainable, prompting consideration of relocation or managed retreat.
- Planning uncertainty: historic records will understate future risk; designs based on past storms may be inadequate.

3) What constraints must these communities take into consideration when planning?
Physical and environmental constraints
- Sea-level rise, storm surge zones, floodplain extent, coastal erosion, subsidence, soil/drainage capacity, and nearby ecosystems (wetlands, barrier islands) that provide natural protection.
Regulatory and legal constraints
- Existing zoning, building codes, federal/state floodplain maps (often lagging behind current/future risk), permitting rules, and property rights.
Financial and economic constraints
- Limited municipal budgets, competing priorities, costs of retrofitting vs. rebuilding, availability and affordability of insurance, and access to state/federal funding or grants.
Technical and data constraints
- Uncertainty in climate projections at local scales, timelines for risk realization, and the need to choose conservative design scenarios (e.g., planning for higher-end sea-level rise).
Social and political constraints
- Community acceptance, equity concerns (vulnerable populations), political will, and the social costs of relocation or restrictive land-use rules.
Operational constraints
- Maintaining evacuation routes, emergency services, utility resilience, and continuity of hospitals and critical infrastructure during and after storms.

Practical planning actions (brief checklist)
- Update hazard maps and adopt forward-looking design standards that incorporate sea-level rise and increased precipitation.
- Restrict new development in highest-risk zones; use setbacks and elevation requirements for coastal and floodplain construction.
- Prioritize nature-based solutions (wetland restoration, coastal buffers) alongside hard defenses where appropriate.
- Invest in stormwater upgrades, pump stations, resilient power/communications, and redundancy for critical services.
- Develop buyout/relocation programs and incentives for managed retreat where rebuilding is unsustainable.
- Strengthen emergency planning, early warning systems, and community outreach; ensure plans address equity and vulnerable populations.
- Secure diversified funding (grants, bonds, public-private partnerships) and update insurance and land-use policies to reflect risk.

Bottom line: Communities should assume future storms will likely be wetter and, in many cases, more damaging. Planning must move beyond historical experience, incorporate climate projections and nature-based defenses, and weigh economic, social and legal constraints when deciding whether to rebuild, elevate, protect, or retreat.