Branko GrisogonoGeofizički odsjek, PMF Zagreb

Hvala: Č. Branković & I. Güttler, DHMZ

Glavne značajke klimatskih promjena i klimatskih

scenarija

OUTLINE Data: Global Past, Present → Future

Clearing out the Denial of Climate Change

Numerical Meteorological & Climate Models Simulators

Climate vs. Weather: expect ≠ get

More of Current Results: Present → Future

Regional Climate Change

Tentative Conclusions → Discussion

Data: Global Past, Present → Future

Clearing out the Denial of Climate Change

Numerical Meteorological & Climate Models Simulators

Climate vs. Weather: expect ≠ get

More of Current Results: Present → Future

Regional Climate Change

Tentative Conclusions → Discussion

5th IPCC, late 2013

observed

data

5th IPCC, late 2013

observed

data,cont’d

Climate last ~ 140 yr: economy ↔ 2 x [economy] ↔ 2 x [CO2, CH4, aerosol, land-use,…] → 2 x [warming,…]≈> Global CO2 as a linear surrogate for all the anthropogenic forcings

b) Residues ≈ Actual T - Anthropogenic T

Mean Residues ≈ ±0.11oC errors in 1-yr GCM hindcasts

Probability that it’s simply a giant natural fluctuation –how much rare?

Estimate the likelihood of a given amount of natural temp. change → bell curve chance of a 1oC fluct. over 125 yr. as natural

is ≈ 1:105 or 1:3 10∙ 6 1oC fluct. ↔ 5 σ

Nonlin. Geophys.→ extremes far stronger than from bell curve; maybe 100 x more likely → 1:1000; yet small enough to reject the possibility

≈2.33 oC /[2 x CO2] ↓

BASIC ISSUES:BASIC ISSUES:

- - MEASUREMENTSMEASUREMENTS, WITH THEIR ERRORS, ARE SPARSE IN SPACE & , WITH THEIR ERRORS, ARE SPARSE IN SPACE & TIME. THUS, INITIAL STATE OF THE ATMOSPHERE & OCEAN IS ONLY TIME. THUS, INITIAL STATE OF THE ATMOSPHERE & OCEAN IS ONLY KNOWN PARTLYKNOWN PARTLY

- NUMERICAL WEATHER PREDICTION (NWP) & CLIMATE - NUMERICAL WEATHER PREDICTION (NWP) & CLIMATE MODELSMODELS CAN'T FULLY RESOLVE IN SPACE & TIME ALL THE RELEVANT CAN'T FULLY RESOLVE IN SPACE & TIME ALL THE RELEVANT PHYSICAL PROCESSES (ASIDE APPROXIMATIONS)PHYSICAL PROCESSES (ASIDE APPROXIMATIONS)

- ATMOSPHERES & OCEANS ARE INHERENTLY CHAOTIC BESIDES- ATMOSPHERES & OCEANS ARE INHERENTLY CHAOTIC BESIDESSTRONG DETERMINISTIC COMPONENTSSTRONG DETERMINISTIC COMPONENTS

- The atmosphere’s behavior is governed by a set of physical conservation laws telling how the air moves (Newton’s laws of motion), about heating-cooling (laws of thermodynamics), roles of moisture…

- The governing Partial Differential Equations (PDE’s) can’t be solved analytically – only numerical (i.e., approximate) solutions are possible

* Given the current state, I.C. & B.C., the equations may be used to pass the info forward in time forecast

* The observations give the sparse current state – an incomplete picture, the weather & climate models may process the obs. → a fuller picture of reality

Unresolved Processes Unresolved Processes Parameterized Parameterized

Parameterized: Radiation, Moist Processes, Turbulence,…

Predictability, like Turbulence, is Flow Dependent

Weather vs. Climate Models

• Resolution & integration length of the governing PDE’s (motion, mass, thermodynamics, spicies)

• Parameterizations (different space - & time-scales) e.g., weather models might have slight drift (may avoid some feedbacks, etc.) …climate modes not!

• Sometimes numerics, due to numerous couplings (feedbacks) being modeled differently, etc.

• Oceans, soil, biosphere, ice,… treated differently

5th IPCC, late 2013 - numerical simulations

Is the extreme weather we see todayreally caused by global warming?

- Claims are made that push beyond what science can tell us. Attributing cause ↔ effect to individual weather events is fiendishly difficult. Climate is about patterns, statistical behavior…

Extreme weather event No global warming link May change with global warming but amount not

established

Evidence of global warming link

Hurricanes X

Tornadoes X

Droughts X

Forest fires X

Heat waves X

Coastal floods X

Earthquakes X

Floods X

srednjak ansambla

HadGEM1

GFDLCM21

EH5OM

RegCM

Temp. at 2m, Summer (2011-2040) - (1961-90) reanalysis obs.

Precipitation, winter (2011-2040) - (1961-90) reanalysis obs.

HadGEM1

GFDLCM21

EH5OM

Ensemble mean

RegCM

Extreme EventsNo. Summertime Warm

DaysNo. Wintertime Cold Days

Courtesy of Damir Počakal, DHMZ

-There is a +trend in the mean duration of hailstone events in cont. Croatia, Počakal (2012) -But typical, standard climate models don't have those variables included yet - should be there!

Average duration of hail episodes: continental Croatia: 4.3 min in 1981-2015, red & 6.3 min over the Polygon (NW Croatia), 2002-2015, blue.

HAIL EPISODES IN CROATIA

Current surface temp. upward trends & future predictions are unusual, unexplained by natural internal climate variability at ≈ 99 % confidence

“Predictions” based on greenhouse gas emission scenarios & links the gases concentrations temp. via modeling & simulations

Included: population growth, economic development, technol. change, social interactions

Besides large spatio-temporal variations, global warming is real, it exceeds in magnitude & pace natural changes over more than the last 103 yr.

No detailed clim. projections for hail-storms and wind fields in/around Croatia

TENTATIVE CONCLUSIONS

Immediate changes seem needed: lowering emissions of green-house gasses to meet the scenario with global ~ +2oC in ≈ yr. 2100

Targeting and promoting more human technologies, renewable energies, healthier food & water Humanistic approach needed!

It is wrong to deploy “instrumental rationalism” (max. efficiency only) & blind pragmatism based on e.g., large resources & markets

Make reliable regional climate – economy projections & space-time variability for next few decades (agronomy, energy, tourism, education, traffic, etc.)

TENTATIVE CONCLUSIONS cont’d

The End

IPCC 2007

ModelSimulations