Happy Golden Anniversary SCOR! From… Trace element cycles in a changing world Gideon Henderson Bob Anderson 2003 meeting - 2 big debates….. Name, and whether to be global change or not.

Iron measurements <-- Before 2003 What we can do now --> From science plan. Old figures, but probably some of the most compelling… Know so little about distribution of TEIs, but there is so much TO know - and an ability to know it for the first time What we can do now -->

GEOTRACES - A trace element timeslice Obviously not measured at single time - decade But… each section done once - captures conditions at a single time - not directly assessing global change Still a strong gc component - understanding the inputs provides knowledge about how they might have changed etc. And proxy developent as mentioned by Jean yesterday. Just getting going - look to the future… .

Trace elements in a changing ocean Monitoring / time-series / sensors Accidental change (e.g. ocean acidification) Intentional change (e.g. geoengineering) Transition Point from Planning to Implementation Timeline

Variable chemical inputs WG 129 - John told us about yesterday Timeline

Arctic Transect Antarctic Transect UK D UK/D/Es USA F F/Can Nl USA/D/Mex F/Es/It Monitoring Linking to existing time-series (including GOOS) And to SCOR programmes - SOLAS, IMBER Very few monitor TEIs Need to explore ways to add TEI measurements to existing and new timeseries stations Sensors… Martin told us about O2 sensors. Nitrate, metals Fe, etc. Coastal models exist

Trace elements in a changing ocean Monitoring / time-series / sensors Accidental change (e.g. ocean acidification) Intentional change (e.g. geoengineering) Transition Point from Planning to Implementation Timeline

Ocean acidification Big uncertainties are biological 0.3 pH unit decrease Leads to 50% decrease in [OH-] Links to IMBER and SOLAS As such - disciplinary mission with clear focus on marine geochemistry Mission

Trace elements in a changing ocean Monitoring / time-series / sensors Accidental change (e.g. ocean acidification) Intentional change (e.g. geoengineering) Transition Point from Planning to Implementation Timeline

As such - disciplinary mission with clear focus on marine geochemistry

Geoengineering Companies actively planning to mess with ocean chemistry to alter the carbon cycle….. By Fe addition or alkalinity addition. Many oceanographers are instinctively opposed to these schemes, and there is a tendency to ignore them. But we have a responsibility to engage with these ideas and test them against the best ocean science. Mission

Trace elements in a changing ocean Monitoring / time-series / sensors Accidental change (e.g. ocean acidification) Intentional change (e.g. geoengineering) Measure, understand and predict trace element cycles in a changing ocean Links to other programmes / WGs: GOOS, IMBER, SOLAS, WG129, WG131… Timeline