Science - USA (2020-07-10)

Chukchi and Barents inflow shelves, where Chla
increased by 26 and 61%, respectively (Fig. 1B
and Table 1). For both regions, three of the
highest years of mean Chlawere measured in
the past 4 years of the time series. Chlaalso
significantly increased in the smaller Baffin

subregion (26%), with much of the increase

occurring in recent years (Table 1). In all re-

maining subregions, Chlashowed no signif-

icant trend between 1998 and 2018 (Table 1).

However, the slope of the Chlatrend in the

shelf subregions shifted more positive between

the first and second decades of the time series

(Table 1). There were areas of intense increases

in Chlaconcentration along the shelf break

of the interior seas, especially immediately

north of the Beaufort, Laptev, and Barents shelf

breaks (Fig. 1B).

SCIENCEsciencemag.org 10 JULY 2020•VOL 369 ISSUE 6500 199

Table 1. Time series trends.Regionaltime series trends for the AO and its subregions. Total percent change for the entire time series as well as slope of the

regression (annual absolute change) for the entire time series (1998–2018), first decade (1998–2008), and the most recent decade (2009–2018) are shown.

Values in parentheses for Chlaare rates of increase in the seasonal maximum Chlaconcentrations, rather than the mean.

1998 – 2018 (% change) 1998–2018 (change year−^1 ) 1998–2008 (change year−^1 ) 2009–2018 (change year−^1 )

OW area (km............................................................................................................................................................................................................................................................................................................................................^2 )

Arctic............................................................................................................................................................................................................................................................................................................................................26.8* 58,952* 95,322* 31,961

Chukchi............................................................................................................................................................................................................................................................................................................................................30.0* 4545* 7387* 2666

Barents............................................................................................................................................................................................................................................................................................................................................24.4* 15,807* 26,184* 11,966

Siberian............................................................................................................................................................................................................................................................................................................................................63.6* 7604* 26,986* 1886

Laptev............................................................................................................................................................................................................................................................................................................................................20.7 1920 764 – 4819

Kara............................................................................................................................................................................................................................................................................................................................................72.7* 8749* 12,722* 1366

Beaufort............................................................................................................................................................................................................................................................................................................................................21.7 788 650 – 1174

Baffin............................................................................................................................................................................................................................................................................................................................................3.6 654 2721 – 2355

Canada............................................................................................................................................................................................................................................................................................................................................7.4 944 – 1286 – 1000

Nordic............................................................................................................................................................................................................................................................................................................................................2.6 1990 277 8971*

Basin............................................................................................................................................................................................................................................................................................................................................123.1* 13,329* 19,567 6204

OW duration (days)............................................................................................................................................................................................................................................................................................................................................

Arctic............................................................................................................................................................................................................................................................................................................................................4.7 0.34 0.30 0.78

Chukchi............................................................................................................................................................................................................................................................................................................................................33.8* 1.77* 3.07* 3.70*

Barents............................................................................................................................................................................................................................................................................................................................................21.2* 3.34* 8.67* 0.58

Siberian............................................................................................................................................................................................................................................................................................................................................35.8* 1.22* 2.30 1.67

Laptev............................................................................................................................................................................................................................................................................................................................................61.7* 2.22* 2.29 –0.13

Kara............................................................................................................................................................................................................................................................................................................................................76.1* 3.18* 4.15* –0.48

Beaufort............................................................................................................................................................................................................................................................................................................................................43.7* 2.18* 1.29 0.09

Baffin............................................................................................................................................................................................................................................................................................................................................4.5 0.32 1.23 –1.68

Canada............................................................................................................................................................................................................................................................................................................................................8.3 0.35 0.95 –0.85

Nordic............................................................................................................................................................................................................................................................................................................................................0.2 0.04 –0.20 0.02

Basin............................................................................................................................................................................................................................................................................................................................................0.0 0.00 1.09 1.52

Chl............................................................................................................................................................................................................................................................................................................................................a(mg m–^3 )

Arctic............................................................................................................................................................................................................................................................................................................................................21.5* 0.007* –0.001 0.013 (0.052*)

Chukchi............................................................................................................................................................................................................................................................................................................................................26.2* 0.017* –0.012 0.036 (0.387)

Barents............................................................................................................................................................................................................................................................................................................................................60.5* 0.022* 0.025 0.021 (0.061)

Siberian............................................................................................................................................................................................................................................................................................................................................–11.3 –0.003 –0.018* 0.003

Laptev............................................................................................................................................................................................................................................................................................................................................10.8 0.003 –0.003 0.001

Kara............................................................................................................................................................................................................................................................................................................................................–22.2* –0.005* –0.008 0.002

Beaufort............................................................................................................................................................................................................................................................................................................................................–17.0 –0.004 –0.008 0.001

Baffin............................................................................................................................................................................................................................................................................................................................................26.4* 0.005* 0.001 0.009

Canada............................................................................................................................................................................................................................................................................................................................................–8.7 –0.003 –0.010 0.005

Nordic............................................................................................................................................................................................................................................................................................................................................–9.8 –0.003 –0.022 0.019*

Basin............................................................................................................................................................................................................................................................................................................................................–15.3 –0.005 0.033 –0.052

Integrated production (Tg C year............................................................................................................................................................................................................................................................................................................................................–^1 )

Arctic............................................................................................................................................................................................................................................................................................................................................56.5* 6.79* 6.47* 8.39*

Chukchi............................................................................................................................................................................................................................................................................................................................................96.1* 1.06* 0.97 1.90*

Barents............................................................................................................................................................................................................................................................................................................................................87.6* 3.73* 4.45* 4.06*

Siberian............................................................................................................................................................................................................................................................................................................................................116.7* 0.37* 0.78* 0.44

Laptev............................................................................................................................................................................................................................................................................................................................................112.1* 0.26* 0.16 –0.02

Kara............................................................................................................................................................................................................................................................................................................................................100.2* 0.35* 0.54* 0.22

Beaufort............................................................................................................................................................................................................................................................................................................................................38.6* 0.05* 0.02 0.01

Baffin............................................................................................................................................................................................................................................................................................................................................26.3* 0.18* 0.17 –0.03

Canada............................................................................................................................................................................................................................................................................................................................................14.4 0.07 –0.08 0.02

Nordic............................................................................................................................................................................................................................................................................................................................................9.0 0.38 –1.22 2.66*

Basin.....................................................................................................................................128.6* .......................................................................................................................................................................................................0.37* 0.75* –0.86

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