Upper bound of nitrogen fixation, estimated from deposited soluble iron, increased by 19–40% from the 1980s to the 2010s, partly offsetting an ~18% decline in direct modeled nitrogen deposition. External nitrogen–fueled net primary primary and export production rose as a results in subtropics.

Wally Broecker's 1975 paper combined early work on climate cycles derived from ice cores with fossil fuel CO2 warming projections; he mentions "man-made dust" as a possible cooling factor but this was before wide-spread recognition of anthropogenic aerosol cooling www.science.org/doi/10.1126/...

Here is a figure showing time moving from right to left from a classic isotope geochemistry paper from 1955 by the legendary Cesare Emiliani who trained with Harold Urey. Who are to argue? Source: Cesare Emiliani, Pleistocene temperatures, Journal of Geology, 63 (6) (1955), pp. 538-577

And congratulations to the full suite of new AMS @ametsoc.org Honorary Members, Medalists and Awardees including my colleague Prof. Inez Fung @ucberkeleyofficial.bsky.social

🌊 article From white to green to blue? Trajectories of phytoplankton communities in a warming Southern Ocean released as review in advance @annualreviews.bsky.social doi.org/10.1146/annu...

Predictions of increasing phytoplankton biomass associated with warming and declining glacial and sea ice are supported by observations. As wind intensity continues to increase and glacial and sea ice decline, however, long-term projections indicate that phytoplankton biomass will decline.

Southern Ocean is experiencing warming, melting of ice, and increasing wind. Changes in ocean physics, in particular mixed layer depth & vertical stratification, affect phytoplankton community through light environment, nutrient supply, and temperature.

Southern Ocean phytoplankton communities exhibit substantial taxonomic diversity that varies geographically and over the growth season. Key groups include: coccolithophores, diatoms, Phaeocystis, silicoflagellates, dinoflagellates & cryptophytes

Following the melt of seasonal sea-ice cover, large phytoplankton blooms form in the Southern Ocean around Antarctic. Image shows seasonal climatology of surface chlorophyll from satellite remote sensing; chlorophyll is a photosynthetic pigment and proxy for phytoplankton

Wildfire smoke causing really poor air quality & visibility today in Charlottesville VA. The hazy hill in the background is Monticello, which is normally crystal clear.

Congratulations to now Dr. Parisa Javadi, who successfully defended her Ph.D. thesis on carbon dioxide removal, integrated assessment models & global climate goals UVA Civil & Environmental Engineering Prof. Andres Clarens @andresclarens.bsky.social @uvaenvironment.bsky.social 1/3

Fossil fuel combustion generates air pollution harming human health (e.g., particles and smog). Climate scenarios the rely heavily on carbon dioxide removal #CDR, rather than decarbonization, result in more residual fossil fuel CO2 emissions, more air pollution, lower human health benefits

Looking forward to symposium celebrating Bill Jenkins and science today @whoi.edu @usocb.bsky.social @solas-ipo.bsky.social sites.google.com/view/jenkins...

Jorge advanced so many aspects of carbon cycle @agu.org Revelle Medal for outstanding contributions in atmospheric sciences, atmosphere- ocean coupling, atmosphere-land coupling, biogeochemical cycles, climate, or related aspects of the Earth system agupubs.onlinelibrary.wiley.com/doi/pdf/10.1...

Congratulations to all of the newly elected members of the American Academy of Arts & Sciences, and in particular Prof. Emeritus Jim Galloway from #UVA @uvaenvisci.bsky.social @uvaenvironment.bsky.social www.amacad.org/new-members-...

Palmer, Antarctic LTER project explores plankton from research ships, small-boat sampling, autonomous gliders, satellites and (of course) numerical models @rucool.marine.rutgers.edu The team recently wrote a review paper on Antarctic pelagic ecosystems on a warming planet doi.org/10.1016/j.tr...

Years with late sea‐ice retreat had higher seasonal production and a greater relative abundance of small phytoplankton Wind‐driven mixing reduced light availability but increased iron availability for phytoplankton in the surface mixed layer

Sea‐ice retreat influences the timing and magnitude of phytoplankton production on the Western Antarctic Peninsula

Modeling study uses a 1-D column model of ocean physics & sea-ice that captures seasonal sea-ice formation & melting and mixed layer deepening and shoaling; simulations include assimilation of satellite sea-ice & sub-surface mooring data 🌊 doi.org/10.1017/jog....

For ocean scientists 🌊 I recommend reading the Finalist in Physical and Mathematical Sciences on air-sea gas exchange. www.pnas.org/doi/10.1073/...

Weekend reading arrived today. Thanks @universitypress.cambridge.org

Snow in C’ville today over lunch

I appreciate the though but I was an undergraduate at the time of the Santa Monica Basin tracer experiment; I met many wonderful future colleagues in addition to the PIs (Jim Ledwell, Andy Watson, and Wally Broecker). Here's a list of participants from they end of their paper

One task completed today in the nice early spring weather in Charlottesville Virginia

Diurnal signal in XCO2 for the Park Falls (a) TCCON and (b) spatially co‐located OCO‐3 versus hourly bin shown in local time. While diurnal cycle is clear with wealth of ground-based TCCON data, satellite OCO-3 data are not yet sufficiently dense to quantify the climatological diurnal cycle

Summary of how N-required to define diurnal cycle varies with diurnal signal across TCCON sites for the diurnal rate of change, plotted as a function of the calculated monthly diurnal change. Observations are plotted in cool colors, and Carbon Tracker model CT2022 data are plotted in warm colors.

a) Diurnal changes in XCO2 calculated from the Park Falls TCCON across all calendar months and (b) the corresponding number of observations per hour required to detect a diurnal rate of change that excludes 0 ppm/hr within two standard deviations of the mean.

Ground-based data show that at least 10 independent observations per hour per month are required to robustly quantify the diurnal cycle. Figure shows standard deviation of bootstrapped diurnal drawdown at Park Falls for two representative months as a function of available number of samples N

Example of diurnal cycle calculation for the month of June at Park Falls from ground-based TCCON data. The diurnal cycle in total column carbon dioxide (XCO2) due to biological CO2 uptake during the day is less than 1 ppm even during the peak growing season

Annual cycle of column XCO2 detrended anomalies at Park Falls, WI. Speard of TCCON data (purple) on any given day arises from interannual variability, synoptic variability, and diurnal fluxes. OCO‐3 XCO2 data (orange) coincident with Park Falls between 2019 and 2025 are overlain on the TCCON data.